JP2007240217A - Fluoroscopic inspection device of semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluoroscopic inspection device of a semiconductor wafer easy of configuration, capable of shortening a detection time without requiring a long time in the transfer of data and deteriorating resolving power and especially suitable for use when a large amount of semiconductor wafers are rapidly inspected to achieve a mass production. <P>SOLUTION: The fluoroscopic inspection device of the semiconductor wafer includes a radiation source 1, a rotary operation means 3 for holding the semiconductor wafer 101 to rotationally operate the same, a line sensor 4 for detecting the dose of radiation transmitted through the semiconductor wafer 101 installed so that the arrangement direction of a sensing part is set to an almost diametric direction with respect to the rotary locus of the semiconductor wafer 101 and an addition means 6 for allowing the radiation intensity data detected by the line sensor 4 to correspond to the angle-of-rotation position of the semiconductor wafer 101 to successively add the same at every sensing part. The position of the abnormal place of the radiation transmittance in the semiconductor wafer 101 is specified on the basis of the radiation intensity data loaded by the addition means 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor wafer fluoroscopic inspection apparatus that detects radiation (X-rays, γ-rays, neutron rays, etc.) transmitted through a semiconductor wafer as an object, and detects an abnormal location of radiation transmittance in the semiconductor wafer. The present invention relates to a semiconductor wafer fluoroscopic inspection apparatus for non-destructively detecting an air chamber formed inside a semiconductor wafer.

  2. Description of the Related Art Conventionally, a fluoroscopic inspection apparatus has been proposed that detects radiation (such as X-rays) that has passed through a subject to detect an abnormal location of radiation transmittance in the subject. Such a fluoroscopic inspection apparatus is used, for example, for inspecting patterns of internal layers such as a multilayer wiring board. This fluoroscopic inspection apparatus is basically the same as a fluoroscopic apparatus that is widely used for medical purposes. However, while a medical fluoroscopic apparatus obtains a transmission image using an X-ray film, The difference is that the sensor output is converted into a digital image and a transmission image is created by image processing.

  Conventionally, as described in Patent Document 1, a radiation detector (line sensor) that has a plurality of sensing units arranged in a linear fashion by allowing radiation (X-rays) that diffuses radially to pass through a subject. There has been proposed a fluoroscopic inspection apparatus that detects radiation transmitted through a subject.

JP 2001-13091 A

  By the way, conventionally, a semiconductor device (integrated circuit) has been proposed in which a large number of circuit patterns are created in parallel on a semiconductor wafer (silicon wafer) and then separated.

  In such a semiconductor device (integrated circuit), there are cases where fine air chambers (bubbles and voids) exist in the semiconductor wafer, but conventionally there has been no technique for inspecting the presence or absence of such air chambers. In a semiconductor device, for further miniaturization, the semiconductor wafer may be thinned by polishing and may be formed on the semiconductor wafer thus thinned. In such a case, the internal air chamber that has not appeared on the surface of the semiconductor wafer becomes obvious by polishing, which may hinder the formation of a circuit constituting the semiconductor device.

  In this way, in semiconductor wafers, the presence of minute internal air chambers, which has not been regarded as a problem in the past, has become a problem, so it is considered to perform a fluoroscopic inspection with a fluoroscopic inspection apparatus that has not been conventionally performed. Has been.

  However, when performing a fluoroscopic inspection of a semiconductor wafer using a conventional fluoroscopic inspection apparatus, if a fluoroscopic image of the entire semiconductor wafer is obtained collectively, a huge two-dimensional sensor is required. End up. That is, the diameter of the semiconductor wafer is, for example, about 200 mm, and a fluoroscopic image magnified 8 to 10 times is obtained by using X-rays that diffuse radially. Then, the diameter required for the two-dimensional sensor is about 2000 mm, and it is extremely difficult to configure a fluoroscopic inspection apparatus. In addition, when such a huge two-dimensional sensor is used, the amount of data to be output becomes enormous and data transfer takes a long time.

  Therefore, a method of obtaining a fluoroscopic image by scanning the semiconductor wafer every predetermined area is considered, but it takes a long time to obtain a fluoroscopic image of the entire semiconductor wafer. Here, if it is attempted to shorten the detection time by increasing the scanning speed, the resolution deteriorates and sufficient detection cannot be performed. In addition, if it is attempted to shorten the detection time by enlarging one scanning area, the amount of data output from the sensor becomes enormous, and it takes a long time to transfer data, resulting in a reduction in detection time. I can't.

  In this case, when a large amount of semiconductor wafers are quickly inspected for mass production, sufficient inspection cannot be performed.

  Therefore, the present invention is proposed in view of the above-described circumstances, and is easy to configure, and does not require a long time for data transfer, and further shortens the detection time without degrading the resolution. In particular, it is an object of the present invention to provide a semiconductor wafer fluoroscopic inspection apparatus that is suitable for use in the case where a large number of semiconductor wafers are rapidly inspected for mass production.

  The semiconductor wafer fluoroscopic inspection apparatus according to the present invention has any one of the following configurations in order to solve the above problems.

[Configuration 1]
A semiconductor wafer fluoroscopic inspection apparatus according to the present invention includes a radiation source that generates radiation and emits it toward a disk-shaped semiconductor wafer that is a subject, a rotation operation unit that holds and rotates the semiconductor wafer, and a linear array. A radiation detector configured to detect the amount of radiation transmitted through the semiconductor wafer for each of the sensing units, the radiation detector having a plurality of sensing units arranged in an approximately radial direction with respect to the rotation trajectory of the semiconductor wafer; Adding means for sequentially adding the radiation intensity information detected by the detector for each sensing unit in correspondence with the rotation angle position of the semiconductor wafer, and based on the radiation intensity information added by the adding means, radiation on the semiconductor wafer The position of the abnormal part of the transmittance is specified.

[Configuration 2]
The semiconductor wafer fluoroscopic inspection apparatus according to the present invention is a semiconductor wafer fluoroscopic inspection apparatus having the configuration 1, and includes a plurality of radiation detectors, and each radiation detector has a distance between each sensing unit and the rotation center of the semiconductor wafer. It is characterized by being installed as a different position.

[Configuration 3]
A semiconductor wafer fluoroscopic inspection apparatus according to the present invention includes a radiation source that generates radiation and emits the radiation toward a semiconductor wafer that is a subject, and a plurality of sensing units arranged in a line, and the amount of radiation transmitted through the semiconductor wafer. A radiation detector for detecting each of the sensing units, a moving operation means for moving these radiation sources and radiation detectors in a direction orthogonal to the arrangement direction of the sensing units in the radiation detector and in the arrangement direction, and a radiation detector And adding means for sequentially adding the radiation intensity information detected by each of the sensing units corresponding to the position of the radiation detector, and based on the radiation intensity information added by the adding means, the radiation transmittance of the semiconductor wafer The position of the abnormal part is specified.

[Configuration 4]
The semiconductor wafer fluoroscopic inspection apparatus according to the present invention is a semiconductor wafer fluoroscopic inspection apparatus having any one of configurations 1 to 3, wherein abnormal portions of radiation transmittance in the semiconductor wafer are air chambers formed in the semiconductor wafer. It is characterized by being.

  In the semiconductor wafer fluoroscopic inspection apparatus according to the present invention having the configuration 1, the radiation intensity information detected by the radiation detector is sequentially corresponded to the rotation angle position of the disk-shaped semiconductor wafer for each sensing portion of the radiation detector. Based on the radiation intensity information added by the adding means for adding, the position of the abnormal portion of the radiation transmittance in the semiconductor wafer is specified, so that the configuration is easy and the amount of data transfer at one time does not become enormous. The detection time can be shortened without degrading the resolution.

  In the semiconductor wafer fluoroscopic inspection apparatus according to the present invention having the configuration 2, since the plurality of radiation detectors are installed at positions where the respective sensing units are located at different distances from the rotation center of the semiconductor wafer, the radiation detector is large-sized. The inspection of the entire region of the semiconductor wafer can be quickly performed without the need for conversion.

  In the semiconductor wafer fluoroscopic inspection apparatus according to the present invention having the configuration 3, the addition means for sequentially adding the radiation intensity information detected by the radiation detector for each sensing unit of the radiation detector in correspondence with the position of the radiation detector. Based on the radiation intensity information added by, the location of the abnormal part of the radiation transmittance in the semiconductor wafer is specified, so the configuration is easy and the amount of data transferred at one time does not become enormous and the resolution is degraded. Thus, the detection time can be shortened.

  In the semiconductor wafer fluoroscopic inspection apparatus according to the present invention having the configuration 4, since the abnormal portion of the radiation transmittance in the semiconductor wafer is an air chamber formed in the semiconductor wafer, the semiconductor wafer is effectively inspected. Can do.

  Thus, since the semiconductor wafer fluoroscopic inspection apparatus according to the present invention is an apparatus that uses radiation such as X-rays, γ-rays, and neutrons, depending on other conventional methods, for example, an infrared type inspection apparatus, It is possible to detect an air chamber that exists inside the semiconductor wafer that could not be detected and does not appear on the surface. When a semiconductor wafer is inspected by a conventional infrared inspection apparatus, it is extremely difficult to detect a wafer having a diameter of about 50 μm even when detecting an air chamber (pinhole) exposed on the surface. .

  Further, in the semiconductor wafer fluoroscopic inspection apparatus according to the present invention, when performing the fluoroscopic inspection, a substance for assisting the inspection which is necessary in the conventional ultrasonic inspection apparatus, for example, a liquid such as pure water is unnecessary. is there. Therefore, in the case of inspecting a delicate object such as a semiconductor wafer, there is no possibility of deteriorating the quality of the semiconductor wafer due to the auxiliary substance, and for the preparation of the auxiliary substance and the removal of the auxiliary substance from the semiconductor wafer. Therefore, the inspection time can be shortened. Further, in this semiconductor wafer fluoroscopic inspection apparatus, the cost for manufacturing auxiliary substances such as ultrapure water for semiconductors is not required, and the cost required for the inspection process can be reduced.

  In other words, the present invention is easy to configure, and does not require a long time for data transfer, and further can reduce detection time without degrading resolution. It is possible to provide a semiconductor wafer fluoroscopic inspection apparatus suitable for use in inspection and mass production.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic diagram showing a configuration of a semiconductor wafer fluoroscopic inspection apparatus according to a first embodiment of the present invention.

  As shown in FIG. 1, this semiconductor wafer fluoroscopic inspection apparatus has an X-ray tube 1 serving as a radiation source that emits radiation, for example, an X-ray beam X toward a semiconductor wafer 101 as a subject. The X-ray tube 1 is controlled by an X-ray control device 2. The semiconductor wafer 101 is installed on the rotation operation mechanism 3. The semiconductor wafer 101 is held and rotated by the rotation operation mechanism 3. In this embodiment, the semiconductor wafer 101 is a disk-shaped semiconductor wafer. The diameter of this semiconductor wafer is, for example, about 200 mm.

  The X-ray beam X emitted from the X-ray tube 1 and transmitted through the semiconductor wafer 101 is detected by the X-ray detector 4 which is a radiation detector. The X-ray detector 4 is a so-called line sensor, and has a plurality of sensing units (pixels) arranged in a line, and the amount of radiation (X dose) transmitted through the semiconductor wafer 101 is detected by each sensing unit. Detect every time. The X-ray detector 4 can detect an X-ray intensity distribution on a straight line formed by each sensing unit with a predetermined spatial resolution. The X-ray detector 4 is installed such that the arrangement direction of the sensing units is substantially the radial direction with respect to the rotation locus of the semiconductor wafer 101.

  As the X-ray detector 4, a commonly used imaging tube type can be used. This type of X-ray detector 4 detects on the principle that the charge charged in proportion to the X-ray dose in the sensing unit is scanned and read by an electron beam. As the X-ray detector 4, for example, a detector having a length of about 20 cm and having about 1000 sensing units can be used. In this case, the size of one sensing unit is about 200 μm.

  Since the X-ray beam X is a beam emitted from the X-ray tube 1 and diffused radially, the X-ray beam X is diffused and detected by the X-ray detector 4 after passing through the semiconductor wafer 101. Therefore, the X-ray detector 4 detects an enlarged transmission image of the semiconductor wafer 101. The enlargement ratio at this time is determined by the ratio between the distance from the X-ray tube 1 to the semiconductor wafer 101 and the distance from the X-ray tube 1 to the X-ray detector 4 and is, for example, about 8 to 10 times.

  The X-ray detector 4 is connected to a detector controller 5 so that the electron beam is controlled by the detector controller 5 and the detected radiation intensity information is amplified. The radiation intensity information amplified by the detector controller 5 is supplied to an adding device 6 serving as an adding means. The adder 6 receives one scan of the detection output of the X-ray detector 4 and converts it into a digital signal. The digital signal is sequentially added to each sensing unit of the X-ray detector 4 and stored in the internal memory. .

  Further, information relating to the rotation angle position of the semiconductor wafer 101 is input from the rotation operation mechanism 3 to the addition device 6, and this addition device 6 adds the radiation intensity information corresponding to the rotation angle position of the semiconductor wafer 101. Go. The rotation angle position of the semiconductor wafer 101 is, for example, a position indicated by a rotation angle from the 0 ° position, where a position of a notch or the like provided in the semiconductor wafer 101 is a 0 ° position.

  The radiation intensity information stored in the internal memory of the adding device 6 is supplied to the image display device 7 and displayed by the image display device 7. As described above, in the radiation intensity information added corresponding to the rotation angle position of the semiconductor wafer 101, the noise component is canceled out and smoothed. The difference with respect to this point will be emphasized.

  FIG. 2 is a schematic diagram showing a configuration of a semiconductor wafer fluoroscopic inspection apparatus according to the present invention.

  In this semiconductor wafer fluoroscopic inspection apparatus, as shown in FIG. 2, an X-ray beam is emitted from the X-ray tube 1 toward the semiconductor wafer 101 and is indicated by an arrow A in FIG. Thus, the semiconductor wafer 101 is continuously rotated. Since the X-ray tube 1 and the X-ray detector 4 are stopped, the X-ray tube 1 and the X-ray detector 4 are relatively moved by rotating the semiconductor wafer 101 in this manner. The top is scanned in the circumferential direction.

  The radiation intensity information detected by the X-ray detector 4 is amplified by the detector controller 5 and supplied to the adding device 6. Since the adding device 6 adds the radiation intensity information in correspondence with the rotation angle position of the semiconductor wafer 101, for example, by adding the radiation intensity information of about 10 rotations, the noise component is canceled and smoothed. In addition, the difference with respect to other portions is emphasized with respect to the abnormal portion of the radiation transmittance in the semiconductor wafer 101.

  FIG. 3 is a graph showing radiation intensity information obtained in the semiconductor wafer fluoroscopic inspection apparatus according to the present invention.

  The radiation intensity information stored in the internal memory of the adding device 6 in this way is displayed by the image display device 7 as shown in FIG. 3, and the position of the abnormal location of the radiation transmittance in the semiconductor wafer 101 is specified. Can do. That is, the position of the abnormal part in the radial direction of the semiconductor wafer 101 is specified depending on which sensing part in the X-ray detector 4 is detected, and the semiconductor wafer 101 when the abnormal part is detected is identified. The position in the circumferential direction of the semiconductor wafer 101 at the abnormal part is specified by the rotation angle position of the above. In this way, the position of the abnormal location of the radiation transmittance in the semiconductor wafer 101 can be specified.

  FIG. 4 is a cross-sectional view showing how radiation passes through a semiconductor wafer in the semiconductor wafer fluoroscopic inspection apparatus according to the present invention.

  As shown in FIG. 4, the abnormal part of the radiation transmittance in the semiconductor wafer 101 is, for example, an air chamber (bubble, void) 101a formed in the semiconductor wafer 101. The X-ray beam is an electromagnetic wave having a short wavelength that passes between atoms of the semiconductor wafer 101. However, if such an air chamber 101a is present in the semiconductor wafer 101, the density of the transmitted substance is different, and the transmittance is increased. There is a difference. Therefore, the presence or absence of the air chamber 101a in the semiconductor wafer 101 can be determined from the difference in the transmittance of the X-ray beam. For example, an air chamber having a diameter of about 50 μm is enlarged to about 400 μm to 500 μm in a radiation transmission image on the X-ray detector 4, so that it can be sufficiently detected by a sensing unit of about 200 μm in the X-ray detector 4. it can. Further, if the enlargement ratio of the radiation transmission image on the X-ray detector 4 is further increased, even a small-diameter air chamber, for example, an air chamber having a diameter of about 10 μm can be detected.

  The X-ray detector 4 is movable in the radial direction of the semiconductor wafer 101 as indicated by an arrow B in FIG. Therefore, even if the length of the X-ray detector 4 is shorter than the radius of the magnified image of the semiconductor wafer 101, by moving the X-ray detector 4 in the radial direction of the semiconductor wafer 101, sequentially, The intensity information of the radiation transmitted through the semiconductor wafer 101 can be obtained on the entire surface of the semiconductor wafer 101.

  In this semiconductor wafer fluoroscopic inspection apparatus, by performing inspection while moving the X-ray detector 4 in the radial direction of the semiconductor wafer 101, the presence / absence and position of an abnormal portion of radiation transmittance on the entire surface of the semiconductor wafer having a diameter of 200mm. Can be completed in 1 minute or less, for example, about 20 to 30 seconds.

[Second Embodiment]
FIG. 5 is a schematic diagram showing the configuration of the semiconductor wafer fluoroscopic inspection apparatus according to the second embodiment of the present invention.

  As shown in FIG. 5, this semiconductor wafer fluoroscopic inspection apparatus is provided with a plurality of X-ray detectors 4 a and 4 b, and the X-ray detectors 4 a and 4 b are separated from the rotation center of the semiconductor wafer 101. You may install so that it may become a mutually different position. That is, one X-ray detector 4a is installed on the outer peripheral side portion including the outer peripheral edge of the semiconductor wafer 101, and the other X-ray detector 4b is installed on the inner peripheral side portion including the central portion of the semiconductor wafer 101. The length of each of the X-ray detectors 4a and 4b can be increased by increasing the length of the semiconductor wafer 101 if no portion of the X-ray detectors 4a and 4b is covered between the side portion and the inner peripheral portion. Even if it is shorter than the radius of the image, radiation intensity information about the entire surface of the semiconductor wafer 101 can be obtained without moving the X-ray detectors 4 a and 4 b in the radial direction of the semiconductor wafer 101.

[Third Embodiment]
FIG. 6 is a schematic diagram showing a configuration in the third embodiment of the semiconductor wafer fluoroscopic inspection apparatus according to the present invention.

  Further, this semiconductor wafer semiconductor wafer fluoroscopic inspection apparatus includes the same X-ray tube and X-ray detector 4 as those in the above-described embodiments, and without rotating the semiconductor wafer 101 as shown in FIG. The semiconductor wafer 101 is scanned by moving the X-ray tube and the X-ray detector 4 in the direction orthogonal to the arrangement direction of the sensing units in the X-ray detector 4 and moving in the arrangement direction. It can also be configured. In this embodiment, the semiconductor wafer 101 does not have to be disk-shaped.

  That is, in this semiconductor wafer fluoroscopic inspection apparatus, an X-ray beam is emitted from an X-ray tube toward the semiconductor wafer 101 by a moving operation mechanism (not shown) as indicated by an arrow C in FIG. The tube and the X-ray detector 4 are moved and operated in a direction perpendicular to the arrangement direction of the sensing units. When the movement operation from one side of the semiconductor wafer 101 to the other side is completed, the movement operation mechanism moves the X-ray tube and the X-ray detector 4 into an array of sensing units as indicated by an arrow D in FIG. Move in the direction. Then, the moving operation mechanism moves the X-ray tube and the X-ray detector 4 from the other side of the semiconductor wafer 101 to one side in a direction perpendicular to the arrangement direction of the sensing units, as indicated by an arrow E in FIG. Manipulate. Further, the moving operation mechanism sequentially moves the X-ray tube and the X-ray detector 4 as indicated by arrows F and G in FIG. 6 and performs scanning over the entire surface of the semiconductor wafer 101.

  When the scanning over the entire surface of the semiconductor wafer 101 is completed in this way, the moving operation mechanism repeats the moving operation of the X-ray tube and the X-ray detector 4 so as to follow the path up to that time, and the semiconductor wafer 101 The scan over the entire surface of 101 is repeated.

  The radiation intensity information detected by the X-ray detector 4 is amplified by the detector controller 5 and supplied to the adding device 6 as shown in FIG. Since the adding device 6 adds the radiation intensity information in correspondence with the position of the X-ray detector 4, for example, by adding the radiation intensity information when the entire surface of the semiconductor wafer 101 is scanned about 10 times. The noise component is canceled and smoothed, and the difference in the radiation transmittance in the semiconductor wafer 101 with respect to the other part is emphasized.

  That is, the radiation intensity information stored in the internal memory of the adding device 6 is displayed by the image display device 7, and the position of the abnormal portion of the radiation transmittance in the semiconductor wafer 101 can be specified. That is, the position of the abnormal part on the semiconductor wafer 101 is specified depending on which sensing part in the X-ray detector 4 detects the abnormal part and in which position the X-ray detector 4 is detected. The In this way, the position of the abnormal location of the radiation transmittance in the semiconductor wafer 101 can be specified.

  In each of the embodiments described above, X-rays are used as radiation. However, the radiation used in the semiconductor wafer fluoroscopic inspection apparatus according to the present invention is not limited to X-rays. A line may be used.

It is a schematic diagram which shows the structure in 1st Embodiment of the semiconductor wafer fluoroscopic inspection apparatus which concerns on this invention. It is a schematic diagram which shows the structure of the said semiconductor wafer fluoroscopic inspection apparatus. It is a graph which shows the radiation intensity information obtained in the said semiconductor wafer fluoroscopic inspection apparatus. It is sectional drawing which shows a mode that a radiation permeate | transmits a semiconductor wafer in the said semiconductor wafer fluoroscopic inspection apparatus. It is a schematic diagram which shows the structure in 2nd Embodiment of the semiconductor wafer fluoroscopic inspection apparatus which concerns on this invention. It is a schematic diagram which shows the structure in 3rd Embodiment of the semiconductor wafer fluoroscopic inspection apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray source 3 Rotation operation mechanism 4 X-ray detector 4a X-ray detector 4b X-ray detector 4c X-ray detector 5 Detector controller 6 Adder 7 Image display apparatus 101 Semiconductor wafer X X-ray beam

Claims (4)

A radiation source that emits radiation and emits it toward a disk-shaped semiconductor wafer that is a subject;
A rotation operating means for holding and rotating the semiconductor wafer;
It has a plurality of sensing units arranged in a line, and the direction of arrangement of these sensing units is set as a substantially radial direction with respect to the rotation trajectory of the semiconductor wafer, and the amount of radiation transmitted through the semiconductor wafer is determined for each sensing unit. A radiation detector to detect;
Adding means for sequentially adding radiation intensity information detected by the radiation detector for each sensing unit in correspondence with a rotation angle position of the semiconductor wafer;
A semiconductor wafer fluoroscopic inspection apparatus characterized in that, based on radiation intensity information added by the adding means, a position of an abnormal portion of radiation transmittance in the semiconductor wafer is specified. Comprising a plurality of said radiation detectors,
2. The semiconductor wafer fluoroscopic inspection apparatus according to claim 1, wherein each of the radiation detectors is installed at a position where each of the sensing units has a different distance from a rotation center of the semiconductor wafer. A radiation source that generates radiation and emits it toward a semiconductor wafer that is the subject;
A radiation detector which has a plurality of sensing units arranged in a line and detects the amount of radiation transmitted through the semiconductor wafer for each sensing unit;
A movement operation means for moving the radiation source and the radiation detector in a direction orthogonal to the arrangement direction of the sensing units in the radiation detector and in the arrangement direction;
Adding means for sequentially adding radiation intensity information detected by the radiation detector to each sensing unit in correspondence with the position of the radiation detector;
A semiconductor wafer fluoroscopic inspection apparatus characterized in that, based on radiation intensity information added by the adding means, a position of an abnormal portion of radiation transmittance in the semiconductor wafer is specified.   4. The semiconductor wafer fluoroscopic inspection apparatus according to claim 1, wherein the abnormal location of the radiation transmittance in the semiconductor wafer is an air chamber formed in the semiconductor wafer. 5.

Images