JP2014109530A - Defect inspection device and defect inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and method for defect inspection, which allow in-line total inspection to be made quickly to check for defects on objects under inspection.SOLUTION: A defect inspection device includes: image acquisition means 121 which acquires a two-dimensional information image and a three-dimensional information image of an object under inspection; three-dimensional inspection area specifying means 122 which adjusts the position of the two-dimensional information image using two-dimensional information produced from the two-dimensional information image acquired by the image acquisition means, and specifies a partial area for performing defect inspection using three-dimensional information from a whole area of the positioned two-dimensional information image; three-dimensional information producing means 123 which produces three-dimensional information just for the partial area specified by the three-dimensional inspection area specifying means from the three-dimensional information image acquired by the image acquisition means; and specified area inspection means which checks for defects on the object under inspection by comparing the three-dimensional information produced for the specified partial area and reference three-dimensional information representing a reference for the object under inspection to pass the inspection.

Description

  The present invention relates to a defect inspection apparatus and a defect inspection method for inspecting defects such as an IC package and a semiconductor wafer.

  For example, in the appearance inspection of an IC package, a semiconductor wafer, etc., a method is known which is performed by applying two-dimensional image processing in order to find these defects. As an example of this method, after imaging an inspection object, a luminance value is calculated from each pixel of this image, and a difference in luminance value, specifically, a difference from a reference luminance value, a difference from surrounding luminance values, etc. There is known a method for detecting a defective portion by the above method (see, for example, Japanese Patent Application Laid-Open No. 2007-155610).

JP 2007-155610 A

  According to the above-described defect inspection apparatus method, it is possible to stably detect dirt, stains, and the like having a two-dimensional defect shape. Further, even if the defect shape is a three-dimensional chip, dent, bulge, warp or the like, the defect can be detected by devising the illumination method.

  However, for example, it is difficult to detect a gently raised defect in a semiconductor wafer itself that forms the substrate of an IC package only by devising a lighting method. In order to detect such a defect that is difficult to detect by two-dimensional image processing, three-dimensional measurement is effective. However, due to problems such as processing time and maintainability, it is difficult to introduce in a production line. Yes.

  In particular, in the manufacturing process of IC packages, etc., in which products must be manufactured in large quantities in a limited short time, it is necessary for 100% inspection in this inspection process to carry out 100% inspection of individual inspection objects by so-called in-line inspection. As a result, the manufacturing time increases, resulting in a time loss in manufacturing time, which not only decreases the manufacturing efficiency of the product but also increases the manufacturing cost.

  On the other hand, when performing inspection using such 3D measurement, in order not to reduce the production efficiency of the product, a specific inspection target for every certain number in the inline without performing an inline exhaustive inspection. When non-total inspection is performed to inspect an object, it is difficult to completely detect defective products, which is a problem.

  In addition, since the structure of a 3D inspection device is generally more complicated than that of a 2D inspection device, in order to inspect all objects to be inspected inline, only the 3D inspection device is installed on the line and the product is inlined. If all the inspections are to be performed, the installation space of the three-dimensional inspection apparatus in the production line is limited, and the production line becomes complicated and redundant.

  An object of the present invention is to provide a defect inspection apparatus and a defect inspection method that enable in-line inspection in a short period when confirming the presence or absence of defects in an inspection object such as an IC package.

In order to solve the above-described problem, a defect inspection apparatus according to claim 1 of the present invention includes:
In the defect inspection device that inspects the inspection object for defects,
Image acquisition means for acquiring an image for creating two-dimensional information and an image for creating three-dimensional information of the inspection object;
Alignment is performed using the two-dimensional information created from the image for creating two-dimensional information acquired by the image acquisition means, and the entire region in the aligned image for creating two-dimensional information is selected. 3D inspection area specifying means for specifying a partial area for performing defect inspection using 3D information;
3D information creating means for creating 3D information only from the partial area specified by the examination area specifying means from the image for creating 3D information acquired by the image acquiring means;
A specification for inspecting whether or not there is a defect in the inspection object by comparing the three-dimensional information created by the above and the reference three-dimensional information that is an inspection-accepted product of the inspection object only in the specified partial region It has an area inspection means.

A defect inspection method according to claim 3 of the present invention is
In the defect inspection method for inspecting the inspection object for defects,
An image acquisition step of acquiring an image for creating 2D information and an image for creating 3D information of the inspection object;
Alignment is performed using the two-dimensional information created from the image for creating two-dimensional information acquired in the image acquisition step, and three-dimensionally is selected from the entire region in the aligned two-dimensional image. A three-dimensional inspection region specifying step for specifying a partial region for performing defect inspection using information;
3D information creation step of creating 3D information only from the partial area specified by the examination area specifying means from the image for 3D information creation acquired in the image acquisition step;
A specification for inspecting whether or not there is a defect in the inspection object by comparing the three-dimensional information created by the above and the reference three-dimensional information that is an inspection-accepted product of the inspection object only in the specified partial region It has a region inspection step.

  According to the defect inspection apparatus according to claim 1 and the defect inspection method according to claim 3, three-dimensionally focusing only on a portion necessary for determining whether or not defect inspection is performed without processing all of the acquired image data. Information is created and compared with the reference 3D information. This eliminates the need to create three-dimensional information based on all of the acquired image data and compare it with the reference three-dimensional information. As a result, it is possible to speed up the inspection time of individual inspection objects for image processing inspection. In particular, it is possible to increase the speed of individual inspection objects when 100% inspection is performed for the presence or absence of defects in a large number of products, so that it is possible to prevent a decrease in product production efficiency without requiring extra time in the inspection process. it can.

A defect inspection apparatus according to claim 2 of the present invention is
The three-dimensional information of the three-dimensional information creating means is a height in a partial area specified by the inspection area specifying means.

  The three-dimensional information can be objectively grasped as information such as the shape of a part constituting each inspection object and the height of a board on which these parts are mounted. If inspection is performed over the entire region imaged of the inspection object based on such height information in the three-dimensional information, the processing takes time, but the defect inspection method according to claim 2 and the defect inspection according to claim 4 According to the method, the effects of claims 1 and 3 can be more effectively exhibited by processing such height information as three-dimensional information only in a specific partial region.

  According to the present invention, it is possible to provide a defect inspection apparatus and a defect inspection method that enable in-line inspection in a short period of time, for example, when confirming the presence or absence of defects in an inspection object such as an IC package.

It is a block diagram which shows schematic structure of the defect inspection apparatus which concerns on one Embodiment of this invention. It is a flowchart of the defect inspection method which concerns on one Embodiment of this invention.

  Hereinafter, a defect inspection apparatus and a defect inspection method using the same according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a defect inspection apparatus according to an embodiment of the present invention.

  The defect inspection apparatus 1 according to the present embodiment is an apparatus that performs defect inspection of an inspection object P that has been transported to the inspection stage by the transport device 50, and is configured as an imaging device 10 that includes a CCD camera and a so-called projector. The projector 20 and the illumination device 30 that irradiates the inspection object P with light, and the control unit 100 having the device control unit 110, the inspection control unit 120, and the memory 130 that sequentially stores necessary information are included. Yes.

  An example of the inspection object P for inspecting defects in the present embodiment is a so-called IC package in which an IC is surface-mounted on a semiconductor wafer serving as a substrate. Hereinafter, the IC package is sequentially described as “inspection object P”. Further, the transfer device 50 is provided in an IC package manufacturing line that continuously manufactures a large number of inspection objects P (P1, P2,...) Having the same shape. In FIG. This shows a state where the inspection stage is temporarily stopped for inspection.

  As described above, the imaging apparatus 10 includes one CCD camera, and for each inspection object P, one image for creating two-dimensional information (see X in FIG. 2) and six images for creating three-dimensional information. Images (see Y1 to Y6 in FIG. 2) are continuously captured at short intervals during a predetermined imaging time. In this embodiment, six images for creating three-dimensional information are picked up in order to improve inspection accuracy. However, the number of picked-up images can be arbitrarily selected according to the three-dimensional measurement method employed. Can do. For example, in the phase shift method employed in this embodiment, three-dimensional information can be created if at least three images are captured.

  The projection device 20 is composed of a projector as described above, and is used for image acquisition for creating three-dimensional information by the phase shift method employed in the present embodiment.

  The illumination device 30 is used when the imaging device 10 acquires a two-dimensional information creation image of the inspection target P, and also when the imaging device 10 and the projection device 20 acquire the above-described three-dimensional information creation image. Used.

  The apparatus control unit 110 of the control unit 100 also controls the conveyance apparatus 50 that conveys the inspection object P in addition to the imaging apparatus 10, the projection apparatus 20, and the illumination apparatus 30 that constitute a part of the defect inspection apparatus 1 described above. Do. The apparatus control unit 110 plays a role of appropriately operating or stopping each of the above-described apparatuses when performing a defect inspection method based on a flowchart described later.

  The inspection control unit 120 of the control unit 100 includes an image acquisition unit 121, an inspection area specifying unit 122, a three-dimensional information creation unit 123, and a defect inspection unit 124, and information necessary for the memory 130 in the control unit 100. Are sequentially stored and taken out from the memory 130 to perform an accurate defect inspection of the inspection object P.

  The image acquisition unit 121 of the inspection control unit 120 acquires a single image for creating two-dimensional information as data using the imaging device 10 and the illumination device 30 each including the CCD camera described above, and the imaging device 10 including the CCD camera. In the case of the present embodiment, using the projection device 20 and the illumination device 30 that are projectors, the three-dimensional information creation image by the phase shift method is acquired as data.

  Note that the lighting method of the lighting device 30 is controlled via the device control unit 110 so as to be different between when the 2D information creation image is captured and when the 3D information creation image is captured.

  In addition, the inspection area specifying unit 122 generates two-dimensional information necessary for comparison with the two-dimensional information serving as a reference for alignment from the image data for two-dimensional information creation captured by the image acquisition unit 121. Above, alignment processing is performed to determine a specific inspection region for comparing the three-dimensional information obtained based on the image for creating the three-dimensional information with the reference three-dimensional information that becomes the inspection pass product of the inspection object. Playing a role.

  Further, the three-dimensional information creation unit 123 serves to create three-dimensional information of only a specific examination region narrowed down by the examination region identification unit 122 from the three-dimensional information creation image captured as data by the image acquisition unit 121. Plays.

  Further, the defect inspection unit 124 serves to inspect the presence or absence of this defect by comparing the three-dimensional information corresponding to only the inspection region specifying unit created by the three-dimensional information creation unit 123 with the reference three-dimensional information. .

  It should be noted that the memory 130 appropriately stores the data of each pixel of the above-described two-dimensional information creation image and the three-dimensional information creation image, three-dimensional information of only a specific examination region created by the above-described three-dimensional information creation unit, and the like. They are stored in advance, stored each time, and the stored contents are erased.

  Next, a specific procedure of the defect inspection method using the defect inspection apparatus according to this embodiment described above will be described based on a flowchart. FIG. 2 is a flowchart of a defect inspection method using the defect inspection apparatus according to the present embodiment. Hereinafter, the steps will be described step by step in this flowchart. The inspection object P manufactured as a product first is transported to the inspection stage via the transport device 50, and is kept stationary for a predetermined short time for imaging at this stage (step S1).

  Then, the inspection object P is brought into an imageable state by the illumination device 30, and an image for creating two-dimensional information is imaged from the upper surface of the inspection object P by the imaging device 10 composed of a CCD camera (step S2).

  Next, the two-dimensional information creation image (see X in FIG. 2) captured in step S2 is taken in as data (step S3). This step S3 is executed by the image acquisition unit 121 of the inspection control unit 120. At this time, before proceeding to step S4 and later described later, as shown by a dotted line in the figure, a defect inspection using the image data for two-dimensional information creation itself may be performed. If it is found that the inspection object has a visible large defect such as a missing part or a mounting state of parts in different directions, the inspection object is determined to be NG (fail) at this stage. The process may proceed to step S12 without performing the defect inspection using the three-dimensional information from step S4 to step S11.

  Next, alignment processing is performed after generating two-dimensional information necessary for comparison with two-dimensional information serving as a reference for alignment from the image data for generating two-dimensional information captured in step S3. (Step S4).

  Next, a region to be inspected based on three-dimensional information described later is determined from the entire region of the two-dimensional information creation image positioned in step S4 (step S5). This inspection area is an area in which a defect in which it is difficult to determine the presence or absence of a defect in the inspection using the two-dimensional information among the entire area of the inspection object may be detected. It is possible to set arbitrarily. For example, as such a defect, in an IC package or the like, a gently raised defect or the like in a substrate portion made of a semiconductor wafer can be considered. In such a case, only the substrate portion on which no component or the like is mounted is inspected. Can be set as Alternatively, the inspection area arbitrarily set may be adjusted by feeding back the data of the two-dimensional information creation image captured in step S3 and the two-dimensional information generated in step S4. Steps S4 and S5 are executed by the inspection region specifying unit 122 of the inspection control unit 120.

  Next, in this embodiment, six images for creating three-dimensional information (in FIG. 2), which are specially imaged by the imaging device 10 composed of the same CCD camera and the projection device 20 composed of a projector similar to those used in step S2. (See Y1 to Y6) (step S6). In addition, since there is no change in the positional relationship between the imaging device 10 and the inspection object P in step S2 and step S6, the regions of the 2D information creation image and the 3D information creation image captured in both steps are exactly the same. It becomes.

  Since the above steps S1 to S6 are performed instantaneously, after these steps are completed, the inspection object is carried out using the transfer device without leaving an interval (step S7).

  The operation timings of the imaging device 10, the projection device 20, the illumination device 30, and the transport device 50 that are operated as necessary in the above steps and the following steps are controlled by the device control unit 110 of the control unit 100.

  Next, only the pixel data in the specific examination area determined in step S5 is extracted from all the pixel data of the six images for creating three-dimensional information captured in step S6 (step S8).

  Next, only three-dimensional information in a specific inspection region corresponding to the pixel data extracted in step S8 is created (step S9). Note that steps S8 and S9 are executed by the three-dimensional information creation unit 123 of the inspection control unit 120.

  Next, the defect detection process of the inspection object is performed by comparing the three-dimensional information in the specific inspection region obtained in step S9 with the reference three-dimensional information (step S10). At this time, the distance between the three-dimensional information of the inspection object and the reference three-dimensional information is calculated for each piece of information corresponding to each pixel, and it is determined whether or not the difference exceeds a predetermined threshold.

  Next, in step S10, whether or not the range exceeding the threshold for separation from the three-dimensional information serving as a reference for the three-dimensional information in the specific inspection region is equal to or greater than a certain value is OK for the product based on the three-dimensional information. / NG (pass / fail) is determined (step S11). Steps S <b> 10 to S <b> 12 are executed by the defect inspection unit 124 of the inspection control unit 120. Next, based on the determination result in step S11, it is determined whether the inspection object is an acceptable product or an unacceptable product, and this is assigned to an acceptable product or an unacceptable product (step S12).

  In the present embodiment, the phase shift method is used as a three-dimensional measurement method, but the method is not necessarily limited to this, and an optical cutting method or a stereo measurement method may be used. However, since the number of images to be captured is smaller when the phase shift is used than when the optical cutting method is used, the amount of information processing can be reduced, and the time required for inspection can be shortened. preferable. Further, the use of phase shift is preferable in that it does not require a complicated configuration as in the stereo measurement method.

  In addition, in step S10 and step S11 described above, for example, a defect inspection of an inspection object is performed from the viewpoint of whether or not the warpage of a semiconductor wafer serving as a substrate in a so-called IC package on which a surface mount component is mounted is within an allowable range. It is preferable to map the information acquired by the three-dimensional measurement and correct the inclination of the inspection object itself in a specific inspection region using the least square method.

  As described above, according to the defect inspection apparatus and the defect inspection method according to the present invention, a stable and accurate defect inspection can be performed at high speed. That is, it is easy to introduce the defect inspection apparatus into the defect inspection process of the production line, and it is possible to inspect all the inspected objects in-line. On the other hand, in the continuous inspection on the production line, the surface of the inspection object and the z-axis in the three-dimensional measurement are not always perpendicular to each other. Therefore, according to the present invention, the inspection accuracy can be increased.

  It should be noted that the above-described embodiment is merely an example of the present invention, and these components and the number thereof can be arbitrarily selected without departing from the scope of the present invention. Therefore, for example, the number of imaging devices is not limited to one, and may be two or more. The type of the imaging device is not limited to a CCD camera, and a CMOS camera or a line sensor camera may be used. In addition, the number of lighting devices may be one or three or more. Moreover, when not using a phase shift method when acquiring three-dimensional information, a projection apparatus can be abbreviate | omitted. Further, the defect inspection method according to the present invention is not limited to the order of the flowchart shown in FIG. 2 (routine procedure), and it goes without saying that the flowchart can be appropriately changed within the scope of the present invention. For example, when a light cutting method is used as a three-dimensional measurement method, or when a line sensor camera is used as an imaging device, the inspection object is not stopped at the time of image capturing, and imaging is performed while being conveyed. Also good.

DESCRIPTION OF SYMBOLS 1 Defect inspection apparatus 10 Imaging apparatus 20 Projection apparatus 30 Illumination apparatus 50 Conveyance apparatus (including inspection stage)
DESCRIPTION OF SYMBOLS 100 Control unit 110 Apparatus control part 120 Inspection control part 130 Memory 121 Image acquisition part 122 Inspection area specification part 123 3D information creation part 124 Defect inspection part P Inspection object X Image for 2D information creation Y Image for 3D information creation

Claims (4)

In the defect inspection device that inspects the inspection object for defects,
Image acquisition means for acquiring an image for creating two-dimensional information and an image for creating three-dimensional information of the inspection object;
Alignment is performed using the two-dimensional information created from the image for creating two-dimensional information acquired by the image acquisition means, and the entire region in the aligned image for creating two-dimensional information is selected. 3D inspection area specifying means for specifying a partial area for performing defect inspection using 3D information;
3D information creating means for creating 3D information only from the partial area specified by the examination area specifying means from the image for creating 3D information acquired by the image acquiring means;
A specification for inspecting whether or not there is a defect in the inspection object by comparing the three-dimensional information created by the above and the reference three-dimensional information that is an inspection-accepted product of the inspection object only in the specified partial region A defect inspection apparatus having an area inspection means.   The defect inspection apparatus according to claim 1, wherein the three-dimensional information created by the three-dimensional information creating unit is a height in a partial region specified by the inspection region specifying unit. In the defect inspection method for inspecting the inspection object for defects,
An image acquisition step of acquiring an image for creating 2D information and an image for creating 3D information of the inspection object;
Alignment is performed using the two-dimensional information created from the image for creating two-dimensional information acquired in the image acquisition step, and the entire region in the aligned image for creating two-dimensional information is selected. A three-dimensional inspection area specifying step for partially specifying a partial area for defect inspection using three-dimensional information;
3D information creation step of creating 3D information only from the partial area specified by the examination area specifying means from the image for 3D information creation acquired in the image acquisition step;
A specification for inspecting whether or not there is a defect in the inspection object by comparing the three-dimensional information created by the above and the reference three-dimensional information that is an inspection-accepted product of the inspection object only in the specified partial region A defect inspection method comprising an area inspection step. The defect inspection method according to claim 3, wherein the three-dimensional information created by the three-dimensional information creating unit is a height in a partial region specified by the inspection region specifying unit.

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