JP2014190797A - Defect inspection device for silicon wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a defect detection rate without rotating a silicon wafer under transportation.SOLUTION: A defect inspection device for a silicon wafer includes: a transportation unit 10 which transports a silicon wafer 80; a first infrared irradiation unit 20 which irradiates, with infrared ray, an area along a line 21 forming +45° with a transport direction P on a lower surface 81 of the silicon wafer when the transported silicon wafer 80 passes a first position 21; a first imaging unit 40 which images scattering transmitted light or normally transmitted light of the infrared light emitted from the first infrared irradiation unit 20 and transmitted through the silicon wafer 80; a second infrared irradiation unit 30 which irradiates, with infrared light, an area along a line 31 forming -45° with the transport direction P on the lower surface 81 of the silicon wafer when the transported silicon wafer 80 passes a second position 31; and a second imaging unit 50 which images scattering transmitted light or normally transmitted light of the infrared light emitted from the second infrared irradiation unit 30 and transmitted through the silicon wafer 80.

Description

  The present invention relates to a silicon wafer defect inspection apparatus for inspecting the presence or absence of defects such as cracks in a silicon wafer.

  This type of defect inspection apparatus is disclosed in Patent Documents 1 to 3, for example. The defect inspection apparatus of the literatures 1 to 3 irradiates a region along a straight line perpendicular to the transfer direction on one surface of the silicon wafer while transferring the silicon wafer as an inspection object to one side, The transmitted light is imaged by a camera. In the image data obtained by imaging, the difference in contrast between the normal part of the silicon wafer and the defective part such as a crack, or the verification process of the image pattern peculiar to the defective part stored in advance is performed. The presence or absence is discriminated.

  In each of the defect inspection apparatuses disclosed in References 1 to 3, infrared light is incident at a right angle on one surface of a silicon wafer, and transmitted light (hereinafter referred to as “regular transmission”) is emitted from the other surface at the same angle as the incident angle. It is also called “light”.)

  Although not described in Patent Documents 1 to 3, the applicant of the present application has an angle θ3 (for example, θ3 = 45 °) other than a right angle from the infrared irradiation unit 91 to the lower surface 81 of the silicon wafer 80 as shown in FIG. The line sensor camera 92 captures scattered light (hereinafter also referred to as “scattered transmitted light”) that is incident upon infrared rays and scattered when passing through the silicon wafer 80. Even in the image data obtained by imaging the scattered transmitted light in this way, the presence or absence of a defect is determined based on the difference in contrast between the normal part of the silicon wafer and the defective part such as a crack. In many cases, image data obtained by imaging light clearly shows a defect image in the obtained image data.

JP 2010-34133 A JP 2011-52967 A JP 2012-2648 A

  By the way, whether it is an inspection apparatus in which the incident angle of infrared rays to the silicon wafer is a right angle or an inspection apparatus having an angle other than a right angle, the defect detection rate depends on the direction of the cracks contained in the silicon wafer. May be extremely worse. For example, as shown in FIG. 7A, when the crack 83 is formed along the conveyance direction (direction indicated by the arrow P) of the silicon wafer 80, and as shown in FIG. In the case where the silicon wafer is formed with an inclination of 45 ° with respect to the transfer direction of the silicon wafer, even if the cracks 83 and 84 have the same size, the former has a lower crack detection rate.

  In order to solve such problems, for example, two inspection positions for infrared irradiation and imaging are provided on the inspection line, and the silicon wafer is rotated 90 ° around the vertical line between the two inspection positions. It is conceivable to install a directional rotating device. By doing so, after the transmitted light is imaged at the first inspection position, the silicon wafer is rotated 90 ° by the direction rotating device, and further, the transmitted light is imaged at the later inspection position, and the orientation of the silicon wafer (crack Can be acquired. In many cases, these two pieces of image data are markedly different from each other in the image affected by the crack. Therefore, the image data affected by the crack is relatively unclear. Even if it cannot be detected, the possibility of detecting a crack from the other image data in which the image portion affected by the crack is relatively clear increases.

  However, if the silicon wafer is rotated 90 ° by the direction reversing device, there is a concern that mechanical vibration during rotation is transmitted to the silicon wafer and the silicon wafer is damaged by the vibration. In addition, if the silicon wafer is rotated by the direction reversing device, a certain amount of time is spent for the rotation processing, and the inspection processing speed in the entire line is greatly reduced.

  The present invention was devised in view of such a problem, and transmits a silicon wafer to one side, irradiates one surface of the silicon wafer with infrared rays, and transmits normal transmission light or scattered transmission light transmitted through the silicon wafer. In a silicon wafer defect inspection apparatus that inspects for the presence of defects such as cracks based on image data obtained by imaging the silicon, it is possible to improve the defect detection rate without rotating the silicon wafer being transferred An object of the present invention is to provide a wafer defect inspection apparatus.

  In order to solve the above-described problem, a silicon wafer defect inspection apparatus according to the present invention includes a transfer unit that transfers a silicon wafer, and the silicon wafer transferred by the transfer unit when the silicon wafer passes through a first position. A first infrared irradiation unit that irradiates an area along a straight line that forms a predetermined first angle with the transfer direction on one surface of the wafer, and the first infrared irradiation unit that irradiates the silicon wafer through the first infrared irradiation unit The first imaging unit that captures the scattered transmitted light or the regular transmitted light and the silicon wafer transported by the transport unit pass through a second position different from the first position. A second infrared irradiation unit that irradiates infrared rays to a region along a straight line that forms a predetermined second angle different from the first angle on the one or the other surface; and the second infrared irradiation. And includes a second imaging unit that captures, the scattered transmitted light or regular transmission light transmitted through the silicon wafer is irradiated from.

  According to the silicon wafer defect inspection apparatus having such a configuration, two types of image data obtained by irradiating infrared rays from different directions to defects such as cracks in the silicon wafer without rotating the silicon wafer are obtained. It is done. If the presence or absence of a defect is determined based on these two types of image data, the defect detection rate can be improved.

  The difference between the first angle and the second angle is preferably about 90 °.

  According to the defect inspection apparatus for a silicon wafer having such a configuration, when two pieces of image data obtained by irradiating infrared rays with an angle difference of 90 ° are compared, images of a part affected by the defect are likely to be significantly different. Therefore, even if a defect such as a crack included in the silicon wafer is directional, there is a high possibility that the defect can be detected from at least one of the image data.

  The angle between the transport direction and the first angle is approximately + 45 °, and the angle between the transport direction and the second angle is approximately −45 °, or the transport direction and the first angle. It is desirable that the angle formed between and the second angle is approximately + 45 °.

  According to the defect inspection apparatus for a silicon wafer having such a configuration, it is possible to determine the presence or absence of a defect based on two image data obtained by irradiating infrared rays with an angle difference of 90 °, so that the defect detection rate can be improved. In addition, the width of the infrared irradiation unit and the imaging unit can be minimized.

  The first infrared irradiation unit is configured to make infrared rays incident on one surface of the silicon wafer at an angle other than a right angle, and the first imaging unit images scattered and transmitted light transmitted through the silicon wafer. The second infrared irradiation unit is configured to make infrared rays incident on one or the other surface of the silicon wafer at an angle other than a right angle, and the second imaging unit is transmitted through the silicon wafer. It is desirable to image scattered transmitted light.

  Since the image data obtained by imaging the scattered transmitted light has a defect image that clearly appears more easily than the image data obtained by imaging the regular transmitted light, the defect detection rate can be further improved.

  The first infrared irradiation unit is configured to make infrared light incident on one surface of the silicon wafer at an angle of about 45 °, and the second infrared irradiation unit is formed on one or the other surface of the silicon wafer. It is further desirable that infrared rays are incident at an angle of about 45 °.

  In the transmitted light image data obtained by injecting infrared rays at an angle of 45 ° with respect to the silicon wafer, a defect image easily appears clearly, so that the defect detection rate can be further improved.

  In the defect inspection apparatus for a silicon wafer having the above-described configuration, the presence or absence of a defect is determined based on the first image data imaged by the first imaging unit, and the second imaged by the second imaging unit. It is desirable to include an image data processing unit that performs a predetermined defect detection process when the presence or absence of a defect is determined based on the image data and the presence of a defect is determined based on at least one of the image data.

  According to the present invention, the detection rate of defects such as cracks in the silicon wafer can be improved without giving mechanical vibration to the silicon wafer or reducing the inspection processing speed.

It is a schematic plan view which shows the defect inspection apparatus of the silicon wafer which concerns on embodiment of this invention. It is A arrow directional view in FIG. It is a B arrow view in FIG. (A) is a schematic diagram which shows the change of the scanning position of the 1st imaging part on the silicon wafer conveyed by one side. (B) is a schematic diagram which shows the change of the scanning position of the 2nd imaging part on the silicon wafer conveyed by one side. It is a figure which shows an image data process part and the related apparatus of the circumference | surroundings. It is the figure which showed a mode that the infrared rays were incident on the lower surface of a silicon wafer at 45 degrees, and the scattered light scattered when it permeate | transmits the inside of a silicon wafer is imaged with a line sensor camera. It is the figure which showed a mode that the silicon wafer which has a crack from which directionality differs was conveyed.

  Hereinafter, a silicon wafer defect inspection apparatus according to an embodiment of the present invention will be described with reference to the drawings. The silicon wafer to be inspected may be either a single crystal silicon wafer or a polycrystalline silicon wafer. As shown in FIGS. 1 to 3, the silicon wafer defect inspection apparatus 100 includes a transport unit 10, first and second infrared irradiation units 20 and 30, first and second imaging units 40 and 50, and image data. It is mainly composed of a processing unit 60 (see FIG. 5), an apparatus frame 70 that supports each unit, and the like.

  The transport unit 10 includes a servo motor 11, a drive shaft 12, a rotational power transmission belt 13, driven shafts 14, 14 ', a conveyor belt 15, and the like. More specifically, the drive shaft 12 is directly connected to the output shaft of the servo motor 11. A pulley 16 is attached to each of the drive shaft 12 and the driven shaft 14, and the rotational power of the servo motor 11 is transmitted to the drive shaft 12 and each driven shaft via the rotational power transmission belt 13 wound around each of the two pulleys 16. It is transmitted to the shaft 14. The drive shaft 12, the driven shafts 14, 14 ', and the like are supported by non-moving portions such as the device frame 70 through predetermined bearings.

  A conveyor belt 15 is wound around the drive shaft 12 and the driven shaft 14 ′, and the driven shaft 14 and the driven shaft 14 ′ in two rows. The conveyor belt 15 rotates by the rotational driving force of the drive shaft 12 or the driven shaft 14 and conveys the silicon wafer 80 placed on the conveyor belt 15 in one horizontal and linear direction. Each row of the conveyor belts 15 is composed of a plurality of conveyor belts 15, and gaps 17 for passing infrared rays to be described later are formed between the conveyor belts 15 in the same row. Of course, the gap 17 has such a size that the silicon wafer 80 conveyed in the horizontal direction does not tilt or shake with respect to the horizontal direction.

  The 1st and 2nd infrared irradiation parts 20 and 30 are comprised by the line light guide etc. which irradiate the infrared rays which this infrared rays generator generated in this infrared ray generator, for example in a line form. As infrared rays to be irradiated, for example, those having a wavelength of 900 nm to 1800 nm can be used.

  When the silicon wafer 80 conveyed by the conveyor belt 15 passes the predetermined first position 21, the first infrared irradiation unit 20 has a predetermined first angle and a conveyance direction on the lower surface 81 of the silicon wafer 80. It is installed so as to irradiate infrared rays onto a region along a straight line (a two-dot chain line indicated by reference numeral 21 in FIG. 1) forming α1 (α1 = + 45 ° in the present embodiment). Further, as shown in FIG. 2, the first infrared irradiation unit 20 is installed so that infrared rays are incident on the lower surface 81 of the silicon wafer 80 at an angle θ1 (θ1 = 45 ° in the present embodiment).

  The 2nd infrared irradiation part 30 is installed in the conveyance direction downstream rather than the 1st infrared irradiation part 20. As shown in FIG. When the silicon wafer 80 conveyed by the conveyor belt 15 passes the predetermined second position 31, the second infrared irradiation unit 30 has a predetermined second angle with the conveyance direction on the lower surface 81 of the silicon wafer 80. It is installed so as to irradiate infrared rays to a region along a straight line (a two-dot chain line indicated by reference numeral 31 in FIG. 1) forming α2 (α2 = −45 ° in the present embodiment). Further, as shown in FIG. 3, the second infrared irradiation unit 30 is installed so that infrared rays are incident on the lower surface 81 of the silicon wafer 80 at an angle θ2 (θ2 = 45 ° in the present embodiment).

  As is apparent from the above description, the first position 21 and the second position 31 are different positions. Further, the straight line that forms the predetermined first angle α1 with the transport direction and the straight line that forms the predetermined second angle α2 with each other are non-parallel to each other.

  The 1st and 2nd imaging parts 40 and 50 are constituted by a camera lens, a CCD line sensor (or CMOS line sensor), etc., for example. The image data captured by these image capturing units 40 and 50 is transferred to an image data processing unit 60 described later. Each imaging unit 40, 50 is fixed to a camera support frame (not shown).

  As shown in FIG. 2, the first imaging unit 40 is opposed to the upper surface 82 of the silicon wafer 80 at a right angle, and is a straight line (denoted by reference numeral 21) that forms the first angle α1 with the conveyance direction shown in FIG. The line sensor row is arranged so as to overlap the two-dot chain line) when viewed from above. The first imaging unit 40 images the scattered and transmitted light that is irradiated from the first infrared irradiation unit 20 to the lower surface 81 of the silicon wafer 80 and transmitted through the silicon wafer 80. Lines 1 to 5 shown in FIG. 4A indicate changes in the scanning position of the first imaging unit 40 on the silicon wafer 80 conveyed to one side. That is, the first imaging unit 40 scans relatively from the line segment 1 to the line segment 2, the line segment 3, the line segment 4, and the line segment 5 with respect to the silicon wafer 80 conveyed in the direction of the arrow P. The position is moved and the entire silicon wafer 80 is scanned. The first imaging unit 40 includes two camera lenses 41 and two line sensors, and this maintains a constant resolution by tilting the line sensor rows by 45 ° with respect to the transport direction. This is to ensure a wide imaging range under the condition. The same applies to the second imaging unit 50 described later.

  As shown in FIG. 3, the second imaging unit 50 is opposed to the upper surface 82 of the silicon wafer 80 at a right angle, and is a straight line (reference numeral 31 indicates the second direction α2 and the conveyance direction shown in FIG. 1. The row of line sensors is arranged so as to overlap the two-dot chain line shown) when viewed from above. The second imaging unit 50 also images the scattered and transmitted light that is irradiated from the second infrared irradiation unit 30 to the lower surface 81 of the silicon wafer 80 and transmitted through the silicon wafer 80. Line segments 1 to 5 shown in FIG. 4B indicate changes in the scanning position of the second imaging unit 40 on the silicon wafer 80 conveyed to one side. That is, the second imaging unit 50 also scans from the line segment 1 to the line segment 2, the line segment 3, the line segment 4, and the line segment 5 relative to the silicon wafer 80 transported in the direction of the arrow P. The position is moved and the entire silicon wafer 80 is scanned.

  As shown in FIG. 5, the image data processing unit 60 is constructed by incorporating a predetermined program into an arithmetic processing unit 61 such as a personal computer and executing the program. The image data processing unit 60 determines whether there is a defect such as a crack in the silicon wafer 80 based on the first image data input from the first imaging unit 40 and the second imaging unit 50 and the second imaging unit 50. Is determined. That is, the image data processing unit 60 determines the presence / absence of a defect based on the first image data, determines the presence / absence of a defect based on the second image data, and based on at least one of the image data When it is determined that there is a defect, a predetermined defect detection process is performed. On the other hand, when no defect is detected for any image data, a predetermined defect non-detection process is performed. Examples of the predetermined defect detection process include a process of displaying information indicating that a defect has been detected on the monitor 62, a process of displaying a defective part image on the monitor 62 together with an image of the entire silicon wafer so as to be distinguishable from a normal part. It is done. The predetermined defect non-detection process includes a process for displaying information on the monitor 62 that no defect has been detected.

  As described above, according to the silicon wafer defect inspection apparatus 100 according to the embodiment of the present invention, two image data captured by irradiating infrared rays to defects such as cracks from different directions without rotating the silicon wafer 80. Can be obtained. In many cases, the obtained two image data are different from each other in the image affected by a crack or the like, and therefore the image portion affected by a defect such as a crack is cracked from one image data that is relatively unclear. Even if the image cannot be detected, the crack can often be detected from the other image data in which the image portion affected by the defect such as a crack is relatively clear. As a result, the defect detection rate is improved.

  Further, according to the silicon wafer defect inspection apparatus 100 according to the embodiment of the present invention, two image data obtained by irradiating infrared rays from different directions to defects such as cracks without rotating the silicon wafer 80 are obtained. Therefore, the defect detection rate can be improved without reducing the inspection processing speed.

  In the above-described embodiment, the first infrared irradiation unit 20 and the second infrared irradiation unit 30 make infrared rays incident on the lower surface 81 of the silicon wafer 80 at an angle (45 °) other than a right angle, and the silicon wafer 80 Although the scattered and transmitted light that has passed through is imaged, even if the incident angle of infrared rays is set at a right angle and the regular transmitted light that has passed through the silicon wafer 80 is imaged by the imaging units 40 and 50, certain defect detection is performed. The rate can be expected to improve. This is because even in the two image data obtained in this case, the images of the portions affected by the cracks and the like are different.

  In the above-described embodiment, the first and second infrared irradiation units 20 and 30 are installed below the transfer path of the silicon wafer 80, and the first and second imaging units 40 and 50 are installed in the silicon wafer 80. However, the first and second infrared irradiation units 20 and 30 are installed on the upper side of the transfer path of the silicon wafer 80, and the first and second imaging units 40 and 50 are set on the silicon wafer 80. It is also possible to install it below the transport path. Further, in the above-described embodiment, either the first infrared irradiation unit 20 or the second infrared irradiation unit 30 is installed on the upper side of the transfer path of the silicon wafer 80, and the infrared irradiation is set on the upper side of the transfer path. It is also possible to install an imaging unit corresponding to the part below the conveyance path of the silicon wafer 80.

  The present invention can be applied to, for example, a defect inspection apparatus that inspects the presence or absence of cracks in a silicon wafer while conveying the silicon wafer to one side on a belt conveyor.

DESCRIPTION OF SYMBOLS 10 Conveyance part 20 1st infrared irradiation part 21 1st position (The straight line which makes a predetermined 1st angle with a conveyance direction)
30 2nd infrared irradiation part 31 2nd position (The straight line which makes a predetermined 2nd angle with a conveyance direction)
Reference Signs List 40 First imaging unit 50 Second imaging unit 60 Image data processing unit 80 Silicon wafer 100 Silicon wafer defect inspection apparatus

Claims (7)

A transfer unit for transferring a silicon wafer;
When the silicon wafer transported by the transport section passes through the first position, infrared rays are irradiated onto a region along a straight line that forms a predetermined first angle with the transport direction on one surface of the silicon wafer. 1 infrared irradiation part;
A first imaging unit that images scattered transmitted light or regular transmitted light that has been irradiated from the first infrared irradiation unit and transmitted through the silicon wafer;
When the silicon wafer transported by the transport section passes through a second position different from the first position, a predetermined direction different from the transport direction and the first angle on one or the other surface of the silicon wafer. A second infrared irradiation unit that irradiates infrared rays to a region along a straight line that forms the second angle;
A second imaging unit that images scattered transmitted light or regular transmitted light that has been irradiated from the second infrared irradiation unit and transmitted through the silicon wafer;
A defect inspection apparatus for a silicon wafer, comprising: The silicon wafer defect inspection apparatus according to claim 1,
A silicon wafer defect inspection apparatus, wherein a difference between the first angle and the second angle is approximately 90 °. The silicon wafer defect inspection apparatus according to claim 1,
A defect inspection apparatus for a silicon wafer, characterized in that an angle formed between a transfer direction and the first angle is approximately + 45 °, and an angle formed between the transfer direction and the second angle is approximately −45 °. . The silicon wafer defect inspection apparatus according to claim 1,
A defect inspection apparatus for a silicon wafer, characterized in that an angle formed by the transfer direction and the first angle is approximately −45 °, and an angle formed by the transfer direction and the second angle is approximately + 45 °. . In the defect inspection apparatus of the silicon wafer of any one of Claims 1-4,
The first infrared irradiation unit is configured to make infrared rays incident on one surface of the silicon wafer at an angle other than a right angle, and the first imaging unit images scattered and transmitted light transmitted through the silicon wafer. Is,
The second infrared irradiation unit is configured to make infrared rays incident on one or the other surface of the silicon wafer at an angle other than a right angle, and the second imaging unit transmits scattered transmission light transmitted through the silicon wafer. An apparatus for inspecting defects of a silicon wafer, characterized in that an image is taken. In the silicon wafer defect inspection apparatus according to claim 5,
The first infrared irradiation unit is configured to make infrared rays incident on one surface of the silicon wafer at an angle of approximately 45 °,
The defect inspection apparatus for a silicon wafer, wherein the second infrared irradiation unit is configured to make infrared light incident on one or the other surface of the silicon wafer at an angle of about 45 °. In the defect inspection apparatus of the silicon wafer of any one of Claims 1-6,
The presence / absence of a defect is determined based on the first image data captured by the first imaging unit, and the presence / absence of a defect is determined based on the second image data captured by the second imaging unit. A silicon wafer defect inspection apparatus comprising: an image data processing unit that performs a predetermined defect detection process when it is determined that there is a defect based on at least one of the image data.

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