TW202243062A - Visual inspection device - Google Patents

Abstract

Provided is a visual inspection device capable of quickly performing a desired inspection on a highly reflective site or on a site which has low reflectivity, even when highly reflective sites and sites having low reflectivity are mixed with one another in an inspection image. Specifically provided is a visual inspection device for inspecting on the basis of an image capturing the appearance of a site to be inspected, the visual inspection device being equipped with an inspection image acquisition unit, a reference image registration unit and an inspection unit, and being characterized in that: the inspection image acquisition unit simultaneously acquires, as inspection images, a first standard inspection image which captures at a first brightness the appearance of the site to be inspected, and a second standard inspection image which captures at a second brightness the appearance of the site to be inspected; the reference image registration unit registers, as reference images, a first standard reference image corresponding to the first brightness and a second standard reference image corresponding to the second brightness; and the inspection unit inspects by comparing the first standard inspection image to the first standard reference image, and also inspects by comparing the second standard inspection image to the second standard reference image.

Description

Appearance inspection device

The present invention relates to an appearance inspection device for comparing an inspection image obtained by photographing the appearance of an inspection target part with a reference image to inspect the inspection target part. For example, it relates to an appearance inspection device that photographs the appearance of semiconductor elements, etc. formed on a wafer, and judges whether the semiconductor elements, etc. are good or bad.

After the semiconductor element is formed by laminating a plurality of semiconductor element circuits (that is, the repeated appearance pattern of the element wafer) on a semiconductor wafer, it is sliced into individual chip parts, and the chip parts are packaged as electronic components. Parts are delivered individually, or assembled into electrical products.

Furthermore, before individual wafer components are singulated, the inspection image obtained by photographing the repeated appearance pattern of the component wafer formed on the wafer is compared with the reference image, and the quality of each wafer component is correlated. inspection (for example, Patent Document 1).

Also, there is known a technique for reducing false detections due to misalignment by aligning an inspection target image and a reference image to detect defects (for example, Patent Document 2). [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2007-155610 [Patent Document 2] Japanese Unexamined Patent Publication No. 2003-4427

[Problem to be Solved by the Invention]

FIG. 8 is an image diagram showing an example of an inspection image Px in the prior art.

In a semiconductor element to be inspected, a wiring circuit pattern, an insulating film, and the like are formed in layers, and a portion Ra with a low reflectance and a portion Rb with a high reflectance are mixed. If there are flaws, foreign objects, or pattern defects (hereinafter referred to as flaws) in the portions Ra and Rb having such different reflectances, it is difficult to inspect all the flaws and the like with one imaging condition.

For example, if the image Px is acquired under imaging conditions suitable for the low-reflectance portion Ra, the desired inspection can be performed on the flaw X1 hidden in the low-reflectance portion Ra included in the image Px, but The portion Rb with high reflectance is overexposed, and the desired inspection cannot be performed on the defect X2 hidden in this portion Rb. On the other hand, if the image Px is acquired with the light intensity or exposure time (imaging conditions) suitable for the part Rb with high reflectance, it is possible to correct the defects hidden in the part Rb with high reflectance included in the image Px. X2 etc. perform the desired inspection, but the defect X1 etc. hidden in the part Ra with low reflectance is underexposed, and the desired inspection cannot be performed on the defect X1 etc. hidden in the part Ra.

In the prior art, in order to perform the desired inspection, it is necessary to change the imaging conditions for the parts Ra and Rb having different reflectances, and divide the imaging into two times, but there are problems of delaying the inspection time and reducing the number of processed sheets per unit time.

Therefore, the present invention was made in view of the above-mentioned problems, and an object of the present invention is to provide an appearance inspection device that can detect parts with high reflectance even if parts with high reflectance and parts with low reflectance are mixed in the inspection image. Any one of the high-level and low-level areas quickly performs the desired inspection. [Technical means to solve the problem]

In order to solve the above problems, one aspect of the present invention is an appearance inspection device characterized in that: It is based on the image obtained by shooting the appearance of the inspection target part, and has: An inspection image acquisition unit that acquires an image obtained by photographing the appearance of an inspection target part as an inspection image; a reference image registration unit, which registers a reference image to be an inspection reference of an inspection image; and an inspection section that performs inspection by comparing the inspection image with the reference image; The inspection image acquisition unit at least acquires a first-level inspection image obtained by photographing the appearance of the inspection target part with a first luminance, and a second-level inspection image obtained by photographing the appearance of the inspection target part with a second luminance different from the first luminance. The inspection image is acquired at once as an inspection image, In the reference image registration unit, a first level reference image corresponding to the first luminance as an inspection reference of the first level inspection image and an inspection reference of the second level inspection image are registered as reference images. And the second level reference image corresponding to the second brightness, The inspection unit performs inspection by comparing the first level inspection image with the first level reference image, and performs inspection by comparing the second level inspection image with the second level reference image.

According to such a situation, The first level inspection image or the second level inspection image captured under imaging conditions with different luminances can be obtained at one time, and can be inspected by comparing each with the first level reference image or the second level reference image. [Effect of Invention]

Even if a portion with a high reflectance and a portion with a low reflectance are mixed in the inspection image, desired inspection can be quickly performed on either a portion with a high reflectance or a portion with a low reflectance.

Hereinafter, the form for implementing this invention is demonstrated using drawing. Furthermore, in the following description, the three axes of the orthogonal coordinate system are set as X, Y, and Z, the horizontal direction is expressed as the X direction and the Y direction, and the direction perpendicular to the XY plane (that is, the direction of gravity) is expressed. for the Z direction. In addition, in the Z direction, the direction against gravity is represented as upward, and the direction in which gravity acts is represented as downward. Moreover, let the direction which rotates around a Z direction as a central axis be a (theta) direction. Here, semiconductor elements etc. which are repeatedly formed at a predetermined vertical and horizontal pitch on the surface of the wafer W will be described based on an example in which the inspection target site Rx is set. Furthermore, the portion Rx to be inspected includes a portion Ra with a low reflectance and a portion Rb with a high reflectance, and flaws X1, X2, etc., which are to be inspected, are included therein.

Fig. 1 is a schematic diagram showing an overall configuration of an example of an embodiment of the present invention. In FIG. 1, each part which comprises the appearance inspection apparatus 1 of this invention is shown schematically.

The appearance inspection device 1 performs inspection based on images obtained by imaging the appearance of the inspection target site Rx. Specifically, the appearance inspection device 1 includes an imaging unit 2 , an inspection image acquisition unit 3 , a reference image registration unit 4 , and an inspection unit 5 . Furthermore, the appearance inspection apparatus 1 includes a wafer holding unit H, a relative moving unit M, a computer CP, a controller CN, and the like.

The imaging unit 2 is for imaging the appearance of the inspection target site Rx. Specifically, the imaging unit 2 outputs the first level inspection image P1 and the second level inspection image P2. Furthermore, the first level inspection image P1 is obtained by photographing the appearance of the aforementioned inspection target part Rx with the first brightness. On the other hand, the second level inspection image P2 is obtained by photographing the appearance of the inspection target portion Rx with a second brightness different from the first brightness. Furthermore, the first level inspection image P1 can also be called a bright condition inspection image, and the second level inspection image P2 can also be called a dark condition inspection image. More specifically, the imaging unit 2 includes an optical path branching unit 2S, a first imaging unit 2A, a second imaging unit 2B, a lens barrel 20, an objective lens 22, a rotator 23, an illuminating unit 24, a half mirror 25, and the like.

The optical path branching unit 2S shares the optical axis with respect to the imaging area F, and branches the imaging optical path into two systems of a first optical path LA and a second optical path LB. Specifically, the optical path branching part 2S branches the imaging optical path 2L that passes through the objective lens 22 and is guided into the lens barrel 20 into two directions (in the figure, the upper side is the first optical path LA, and the right side is the second optical path LB). . More specifically, the optical path branching part 2S is composed of an optical element called a beam splitter, and makes a part (for example, 50%) of the light incident from below the optical path branching part 2S straight forward, and upwards as the first optical path. LA is emitted, reflected on a part (for example, 50%), and emitted to the right as the second optical path LB.

The first imaging unit 2A captures the imaging area F via the first optical path LA. Also, the second imaging unit 2B images the imaging area F via the second optical path LB. Furthermore, the brightness of the images captured by the first imaging unit 2A and the second imaging unit 2B are set to different conditions.

Specifically, the first imaging unit 2A sets the imaging conditions related to the brightness of the captured image (exposure time, shutter speed, gain, aperture, or light amount, etc.) to the first level (also referred to as bright conditions). And the person who takes the inspection image. More specifically, the first imaging unit 2A includes an imaging camera 26A, an imaging lens 28A, an ND filter 29A, and the like. The imaging camera 26A includes an imaging element 27A, and outputs a captured image to the outside as a video signal or image data. Specifically, the imaging camera 26A can be exemplified by one including a CCD, a CMOS image sensor chip, or the like as the imaging element 27A. The imaging lens 28A forms an image of the light beam incident through the first optical path LA on the imaging element 27A. The ND filter 29A attenuates the light intensity of the light incident on the imaging element 27A through the first optical path LA. Specifically, the ND filter 29A absorbs part of the incident light and passes (also referred to as transmission) the light therein. More specifically, as the ND filter 29A, one having a transmittance of 99% (attenuation rate of 1%) in the wavelength band that is the light-receiving sensitivity of the imaging element 27A is exemplified.

Specifically, the second imaging unit 2B sets the imaging condition to a second level (also referred to as dark condition) different from the above-mentioned first level, and captures an inspection image. More specifically, the second imaging unit 2B includes an imaging camera 26B, an imaging lens 28B, an ND filter 29B, and the like. The imaging camera 26B includes an imaging element 27B, and outputs a captured image to the outside as a video signal or image data. Specifically, the imaging camera 26B can be exemplified by one including a CCD, a CMOS image sensor chip, or the like as the imaging element 27B. The imaging lens 28B forms an image of the light beam incident through the second optical path LB on the imaging element 27B. The ND filter 29B attenuates the light quantity of the light incident on the imaging element 27B through the second optical path LB. Specifically, the ND filter 29B absorbs part of the incident light and passes (also referred to as transmission) the light therein. More specifically, as the ND filter 29B, one having a transmittance of 1% (attenuation rate of 99%) in the wavelength band which is the light-receiving sensitivity of the imaging element 27B is exemplified.

Note that the imaging by the first imaging unit 2A and the imaging by the second imaging unit 2B are performed simultaneously or within a short period of time. Specifically, when an emission signal is output from the control unit CP to the illumination unit 24 to irradiate the illumination light L1, both the first imaging unit 2A and the second imaging unit 2B are used to perform imaging, and the imaging to the second imaging unit 24 is performed simultaneously. An imaging trigger output of the 1 imaging unit 2A, and an imaging trigger output to the second imaging unit 2B. Furthermore, the "simultaneous" mentioned here is not only completely zero time lag, but also includes the following cases, that is, considering the delay time of the periodic processing of the control device, etc., there is a deviation in the degree of processing that is considered to be performed at the same time time for signal output. In addition, before the output of the light emission signal to the lighting unit 24, in the state where both the first imaging unit 2A and the second imaging unit 2B can be photographed, before the respective exposure times elapse, the signal output to the lighting unit 24 is output. The situation of the light emitting signal of 24 (that is, emitting the common illumination light L1) is also included in the "simultaneous shooting". Also, the term "short time period" means an allowable time lag so that the inspection time does not greatly delay.

More specifically, the first level inspection image P1 and the second level inspection image P2 captured by the imaging cameras 26A and 26B are output as video signals or video data to the outside (in this embodiment, the inspection image acquisition unit 3).

The lens barrel 20 fixes the optical path branching part 2S and the first imaging part 2A and the second imaging part 2B in a specific positional relationship. Specifically, the lens barrel 20 is formed in a substantially T-shape and has a hollow inside (also known as a cavity) so as to shield the external light and introduce the observation light L2 incident from the objective lens 22 to the first imaging unit 2A and the second imaging unit 2B. Called hollow) cylindrical. Moreover, a rotator 23 is installed on one end side (downward in the figure) of the lens barrel 20, and a first imaging unit 2A and a second imaging unit 2B are installed on the other end side (upper and rightward in the figure). Inside the barrel 20, an optical path branching portion 2S is installed. In addition, the lens barrel 20 shown in this example has a double-branched structure, and an illuminating unit 24 and a half mirror 25 are installed between the rotator 23 and the optical path branching part 2S. Further, the lens barrel 20 is attached to the device frame 1f via a connecting metal fitting or the like (not shown).

The objective lens 22 forms an image of the imaging area F on the wafer W on the imaging elements 27A, 27B of the imaging cameras 26A, 26B at different specific observation magnifications. Specifically, the objective lens 22 is comprised including the objective lens 22a, 22b with which magnification differs. Furthermore, the objective lens 22 is arranged at a predetermined distance from the surface of the wafer W (that is, the surface on which the appearance of the portion to be inspected is formed).

The rotator 23 switches the magnification of the objective lens 22 used. Specifically, a plurality of objective lenses 22a and 22b with different magnifications are installed on the rotator 23, and the lens magnifications can be switched by rotating and stationary at a specific angle successively based on manual or external signal control.

The illuminating unit 24 emits the illuminating light L1 required for imaging. Specifically, the lighting unit 24 can be exemplified by laser diodes, metal halide lamps, xenon lamps, LED lighting, etc., based on external signal control to switch on/off, or strobe light at specific places or timings.

The half mirror 25 reflects the illumination light L1 emitted from the illumination unit 24 to irradiate the wafer W side, and passes the observation light L2 incident from the wafer W side to the imaging unit 3 side.

Since the imaging unit 2 has such a configuration, it is possible to combine the first horizontal inspection image P1 captured under bright conditions and the second horizontal inspection image captured under dark conditions for one inspection target site Rx. P2 is taken as an inspection image at the same time or in a short period of time.

The inspection image acquisition unit 3 acquires the external appearance image of the inspection target site Rx as an inspection image. Specifically, the inspection image acquisition unit 3 combines the first level inspection image P1 obtained by imaging the appearance of the inspection target part Rx with the first luminance, and the inspection target part Rx imaged with the second luminance different from the first luminance. The second-level inspection image obtained from the external appearance is obtained as an inspection image at one time. More specifically, the inspection image acquisition unit 3 is constituted by an input unit of a computer CP. Furthermore, the "one-time acquisition" mentioned here means acquisition within the same "simultaneous" or "short period of time" as above.

Fig. 2 is a conceptual diagram showing a state of a photographed appearance image of an example of an embodiment of the present invention. In FIG. 2 , the following state is shown, that is, using the imaging cameras 26A and 26B of the imaging unit 2, while moving relative to the wafer W in the direction indicated by the arrow Vs, images are sequentially captured on the wafer W. Appearance of an element wafer C formed at a specific pitch along the XY direction. The inspection images P1 and P2 captured by the cameras 26A and 26B are sequentially output.

Specifically, during the relative movement of the relative moving part M (for example, moving in the direction of the arrow Vs), the illuminating part 24 is made to strobe and emit light at predetermined intervals or positions, and the imaging cameras 26A and 26B are used to shoot images similar to still images. The appearance image. Then, external appearance images output from the imaging cameras 26A, 26B are acquired from the input unit of the inspection image acquisition unit 3 as inspection images P1, P2.

Since the inspection image acquisition unit 3 is configured in this way, the first level inspection image P1 photographed under bright conditions and the second horizontal inspection image P1 photographed under dark conditions can be acquired at once for one inspection target site Rx. The level inspection image P2 is acquired as an inspection image.

Fig. 3 is a schematic diagram of main parts showing an example of an embodiment of the present invention. FIG. 3( a ) schematically shows a first level image P1 captured by the imaging unit 2 and acquired by the inspection image acquisition unit 3 . FIG. 3( b ) schematically shows the second level image P2 captured by the imaging unit 2 and acquired by the inspection image acquisition unit 3 .

The reference image registration unit 4 registers a reference image as an inspection reference of an inspection image. Specifically, in the inspection reference image registration unit 4, a first horizontal reference image Pf1 corresponding to the first luminance as an inspection reference of the first horizontal inspection image P1 or a second horizontal inspection image P2 is registered. The inspection standard is the second level reference image Pf2 corresponding to the second brightness. In addition, the 1st horizontal reference image Pf1 is also called the reference image of a bright condition, and the 2nd horizontal reference image Pf2 is also called the reference image of a dark condition.

More specifically, the inspection reference image registration unit 3 is constituted by a memory unit or an auxiliary memory unit of the computer CP.

Fig. 4 is an image diagram showing an example of a reference image of an example of an embodiment of the present invention. FIG. 4( a ) shows an example of the first horizontal reference image Pf1 , and FIG. 4( b ) shows an example of the second horizontal reference image Pf2 .

The first level reference image Pf1 is used as a reference for the inspection of the inspection target part Rx, and thus can be exemplified by imaging a part without defects or the like under the same imaging conditions as the first level inspection image P1.

The second level reference image Pf2 is used as a reference for the inspection of the inspection target part Rx, and thus can be exemplified by imaging a part without defects or the like under the same imaging conditions as the second level inspection image P2.

The inspection unit 5 is an inspector who compares the inspection image with the reference image. Specifically, the inspection unit 5 performs inspection by comparing the first level inspection image P1 with the first level reference image Pf1 , and performs inspection by comparing the second level inspection image P2 with the second level reference image Pf2 . More specifically, the inspection unit 5 is composed of a processing unit of a computer CP, an image processing unit, and an execution program, and is configured to perform the following processing. For example, for each pixel of the first horizontal inspection image P1, the inspection unit 5 performs an evaluation of the luminance value of the pixel in the first horizontal reference image Pf1 corresponding to the position of the inspection target part Rx (for example, R1, R2). By comparison, it is judged whether the brightness difference is within a specific range (that is, within the qualified standard), whether pixels with large brightness differences are continuous or aggregated, and so on. Furthermore, for each pixel of the second level inspection image P2, the inspection unit 5 performs a luminance value etc. By comparison, it is judged whether the brightness difference is within a specific range (that is, within the qualified standard), whether pixels with large brightness differences are continuous or aggregated, and so on.

Fig. 5 is an image diagram showing an example of inspection results of an example of an embodiment of the present invention. As an example of inspection results, Fig. 5(a) shows an example of the luminance difference (difference) ΔP1 obtained by comparing the first level inspection image P1 with the first level reference image Pf1, and Fig. An example of the brightness difference (difference) ΔP2 obtained by comparing the level inspection image P2 with the second level reference image Pf2. Furthermore, the difference ΔP1 includes information indicating that the flaw X1 exists in the portion Ra with a low reflectance, and the difference ΔP2 includes information indicating that the flaw X2 exists in the portion Rb with a high reflectance.

The wafer holding unit H holds the wafer W. Specifically, the wafer holding unit H is a supporter that holds the wafer W in a horizontal state from the lower surface side. More specifically, the upper surface of the wafer holding portion H has a horizontal mounting table H1. The mounting table H1 is provided with grooves or holes at the portion in contact with the wafer W, and these grooves or holes are connected to a negative pressure generating mechanism such as a vacuum pump through a switching valve or the like. Then, the wafer holding unit H holds or releases the holding of the wafer W by switching these grooves or holes to a negative pressure state or an air release state.

The relative moving part M is for relatively moving the wafer holding part H and the imaging part 3 . Specifically, the relative movement unit M is configured to include an X-axis slider M1, a Y-axis slider M2, and a rotation mechanism M3.

The X-axis slider M1 is installed on the device frame 1f so that the Y-axis slider M2 moves at an arbitrary speed in the X direction and remains stationary at an arbitrary position. Specifically, the X-axis slider is composed of a pair of rails extending in the X direction, a slider portion that moves on the rails, and a slider drive portion that moves and stops the slider portion.

The Y-axis slider M2 moves the rotation mechanism M3 at an arbitrary speed in the Y direction based on a control signal output from the control unit CN, and stops at an arbitrary position. Specifically, the Y-axis slider is composed of a pair of rails extending in the Y direction, a slider portion that moves on the rails, and a slider driving portion that moves and stops the slider portion.

The slider driving parts of the X-axis slider M1 and the Y-axis slider M2 can be composed of a combination of rotating and stationary servo motors or pulse motors and ball screw mechanisms controlled by signals from the control part CN, or linear motor mechanisms, etc. constitute.

The rotation mechanism M3 rotates the stage H1 at an arbitrary speed in the θ direction, and is stationary at an arbitrary angle. Specifically, the rotation mechanism M3 can be exemplified by a direct-drive motor or the like controlled by a signal from an external device and rotated/stationary at an arbitrary angle. On the rotation side member of the rotation mechanism M3, the mounting table H1 of the wafer holding part 2 is attached.

Since the relative moving part M is configured in this way, it is possible to move the wafer W relative to the imaging part 2 in the XYθ direction independently or in combination at a specific speed or The angle moves relative to each other, or stays still at any position and angle.

A computer CP is one that inputs signals or data from the outside, performs specific calculation processing or image processing, and outputs signals or data to the outside, for example, it performs the following functions. ・Registration of pixel pitch or imaging magnification of video cameras ・Registration of inspection process (imaging position, imaging sequence, or imaging interval (pitch, section), moving speed, etc.), switching of the inspection process used, etc. ・Image processing of acquired inspection images P1, P2, etc. More specifically, the computer CP is composed of an input unit and an output unit, a memory unit (called a temporary register or a memory), a control unit and an operation unit (called a CPU or MPU), an image processing device (called a GPU) , an auxiliary storage device (HDD or SSD, etc.) (that is, hardware), and an execution program thereof (that is, software).

The controller CN is used to input and output signals or data with external devices (wafer holding unit 2, imaging unit 3, relative moving unit M, etc., or computer CP) to perform specific control processing, for example, to perform the following functions By. ・Output signal of hold/release of wafer W to wafer holding unit 2 ・Control the rotator 23 to switch the objective lens 22 used (magnification) ・Output strobe light signal to the lighting unit 24 ・Output imaging trigger to video camera 26A, 26B ・Input of inspection images P1, P2 output from cameras 26A, 26B ・Drive control of the relative moving part M: While monitoring the current positions of the X-axis slider M1, the Y-axis slider M2, and the rotation mechanism M3, it is a function to control by outputting a driving signal That is, the controller CN can drive and control the relative movement unit M, and can output an imaging trigger to the imaging unit 2 while changing the position of the imaging region F set on the wafer W. Furthermore, it is possible to switch the imaging magnification or the size of the field of view according to the type of inspection, and output an imaging trigger while changing the interval between imaging, so that a desired image can be obtained.

Furthermore, the output of the imaging trigger can be exemplified as follows. ・A method of making the illumination light L1 emit light for a very short time (so-called strobe light) every time a certain distance is moved while scanning and moving in the X direction. ・The method of moving to a specific position and standing still and irradiating the illumination light L1 to shoot (so-called step & repeat).

More specifically, the controller CN is composed of a part of the computer CP or a dedicated programmable logic controller (ie, hardware), and the execution program (ie, software).

＜Operation flow＞ Fig. 6 is a flowchart of an example of an embodiment of the present invention. FIG. 6( a ) shows a sequence of steps in which the visual inspection apparatus 1 captures and registers an image (namely, a reference image) serving as an inspection reference of the component wafer C placed on the wafer W for each operation step. This is referred to as a reference image registration flow, and a mode that operates according to the following operation flow is the reference image registration mode.

First, in order to register a reference image, the wafer W is placed on the stage H1 of the visual inspection apparatus 1 (step s1 ). The wafer W includes an element wafer C (so-called good-quality wafer) as a standard for judging whether it is good or bad.

Next, the alignment marks and the like formed on the wafer W are read to align the wafer W (step s2 ).

Next, the relative moving unit M is controlled to move the wafer W to a position where the device wafer C set as a reference image can be taken by the imaging unit 2 (ie, an imaging position) (step s3).

Next, the first level reference image Pf1 is captured by the first imaging unit 2A, the second level reference image Pf2 is captured by the second imaging unit 2B, and these are registered as reference images in the inspection reference image registration unit 3 ( step s4).

Furthermore, it is judged whether to photograph and register the reference image (step s5), and the above-mentioned steps s3 to s5 are repeated when photographing and registering. On the other hand, if there is no need to further capture and register the reference image, the wafer W is discharged (step s6).

Then, it is judged whether to use another wafer W to shoot and register another reference image (step s7), and the above steps s1-s7 are repeated when continuing to shoot and register. On the other hand, if there is no need to continue shooting and registering the reference image, a series of processes ends.

FIG. 6( b ) shows a series of procedures in which the external appearance image of the component wafer C arranged on the wafer W is captured by the external appearance inspection device 1 and the inspection is performed based on the image for each operation step. This is called an inspection flow, and a mode that operates according to the following operation flow is an inspection mode.

First, an inspection recipe is set in the new registration, or is selected from pre-registered inspection recipes, and the wafer W is placed on the mounting table H1 (step s11 ).

Next, the alignment marks and the like formed on the wafer W are read to align the wafer W (step s12 ).

Next, the relative moving part M is controlled to move the wafer W and image the element wafer C by the imaging part 2, the first level inspection image P1 by the first imaging part 2A, and the second level inspection image P1 by the second imaging part 2B. The image P2 is acquired at once by the inspection image acquisition unit 3 using the images P1 and P2 as inspection images (step s13 ).

Then, the obtained first level inspection image P1 is compared with the pre-registered first level reference image Pf1 for inspection, and the obtained second level inspection image P2 is compared with the pre-registered second level reference image Pf1. The image Pf2 is compared and checked (step s14).

Then, it is judged whether to continue to acquire other inspection images for inspection etc. (step s15), if it is necessary to continue the inspection etc., repeat the above steps s13-s15. On the other hand, if there is no need to continue inspection or the like, the wafer W is discharged (step s16 ).

Then, it is judged whether the inspection image acquisition and inspection are also performed on other wafers (step s17), and if further inspection is to be performed, the above-mentioned steps s11-s17 are repeated. On the other hand, if no further inspection or the like is required, a series of processes are ended.

Since the appearance inspection device 1 of the present invention is configured in this way, the first level inspection image and the second level inspection image taken under different imaging conditions can be obtained at one time, and each can be compared with the first level reference map. The image is checked by comparing it with the second level reference image. Therefore, even if a portion with a high reflectance and a portion with a low reflectance are mixed in the inspection image, desired inspection can be quickly performed on either a portion with a high reflectance or a portion with a low reflectance.

(other forms) In addition, in the above, as the appearance inspection device 1 , the following configuration is exemplified, that is, the imaging unit 2 is provided, and the inspection image acquisition unit 3 acquires the first level inspection image with different brightness captured by the imaging unit 2 . P1 and the second level check image P2. With such a configuration, it is only necessary to perform one round of sequential imaging of the inspection target site Rx while moving the wafer W and the imaging unit 3 relative to each other, and the inspection images P1, P2 can be obtained at each imaging site at one time. That is, it is not necessary to change the imaging conditions of the same inspection target site Rx to perform the second round of imaging (the imaging does not need to be divided into two times) as in the prior art. Therefore, the inspection time can be shortened, and the number of sheets processed per unit time can be increased.

However, in actualizing the present invention, the imaging unit 2 is not essential, and may be configured such that, in cooperation with an external device, the inspection image acquisition unit 3 acquires the inspection image P1 output from the external device at one time. , P2 are compared and checked with the reference images Pf1 and Pf2.

(About the reference image and inspection department) In addition, in the above, the following configuration was exemplified, that is, in the inspection unit 5, the first level inspection image P1 obtained by shooting with the first brightness (bright condition) and the first brightness (bright condition) were combined with the first brightness (bright condition). Comparing the corresponding first level reference image Pf1, the second level inspection image P2 captured with the second brightness (dark condition) and the second level reference image Pf2 corresponding to the second brightness (dark condition) Compare and check. In this case, the luminance differences (differences) ΔP1 and ΔP2 of the respective pixels to be compared may be output as inspection results, respectively, or may be added as one and output as inspection results.

However, the external appearance inspection apparatus 1 is not limited to such a structure, Even if it is another structure, this invention can be actualized. For example, the configuration is such that, among the inspection target parts Rx, the part to be inspected based on the image acquired with the first luminance (bright condition) and the part to be inspected based on the image acquired with the second luminance (dark condition) are predetermined. parts. in particular, The position information of the part inspected with the first luminance among the parts to be inspected Rx is defined in association with the first level reference image, The positional information of the part inspected with the second luminance among the parts to be inspected Rx is defined in association with the second level reference image, The inspection unit 5 is configured as follows: The first level inspection image P1 and the first level reference image Pf1 are inspected by comparing the parts inspected with the first luminance (in this example, the parts Ra with low reflectance), The inspection is performed by comparing the second level inspection image P2 and the portion inspected with the second luminance (in this example, the portion Rb with high reflectance) in the second level reference image Pf2.

Furthermore, the position information of the part inspected with the first brightness is based on which part the comparison object between the inspection image and the reference image is located, or the coordinates in the first level inspection image P1 or the first level reference image Pf1 (Defined based on the relative coordinates of the corners of the image, or based on the relative coordinates of markers serving as a reference for position positioning within the image, etc.), etc.). On the other hand, the position information of the part inspected with the second luminance is based on which part the comparison object between the inspection image and the reference image is located, or the second level inspection image P2 or the second level reference image Pf2. Coordinates (based on the relative coordinates of the corners of the image, or based on the relative coordinates of a mark serving as a reference for position positioning within the image, etc.) and the like are defined.

According to such a configuration, an overexposed portion in the first level inspection image or an underexposed portion in the second level inspection image can be excluded from the object to be compared with the reference image. Therefore, it is preferable that the area of the inspection target part of the comparative processing is reduced and the inspection time can be shortened.

In addition, in the above, the structure which registers the 1st horizontal reference image Pf1 and the 2nd horizontal reference image Pf2 separately is illustrated with respect to the reference image registration part 4. As shown in FIG. With such a configuration, inspection is performed by comparing the first level inspection image P1 with the first level reference image Pf1 by the inspection unit 5, and the second level inspection image P2 is compared with the second level reference image Pf2. And carry out the inspection, and the desired inspection can be carried out. With such a configuration, the main processing of the inspection unit 5 only needs to be the comparison processing for calculating the brightness difference, so the processing time can be shortened, which is preferable.

Moreover, the external appearance inspection apparatus 1 may be comprised as follows. For example, assume a configuration in which the part Ra serving as the inspection standard under the first luminance (bright condition) and the part Rb serving as the inspection standard under the second luminance (dark condition) are precombined into 1 as the reference image Pfz. Register each image, combine the part Ra which is the inspection object under the first luminance (bright condition) and the part Rb which is the inspection object under the second luminance (dark condition) as the inspection image Pz to form a single image , and compare and check with the reference image Pfz.

Specifically, the appearance inspection device 1 is configured to include an inspection image synthesis unit 6 in addition to the above configuration (see FIG. 1 ).

Fig. 7 is an image diagram showing an example of an inspection image and a reference image of still another example of an embodiment of the present invention. FIG. 7( a ) shows an example in which a region Ra which is an inspection object under bright conditions and a region Rb which is an inspection object under dark conditions are synthesized into one image as an inspection image Pz and registered. FIG. 7( b ) shows an example in which a part Ra serving as an inspection standard under bright conditions and a part Rb serving as an inspection standard under dark conditions are synthesized into one image and registered as a reference image Pfz.

The inspection image synthesis unit 6 combines the first level inspection image obtained by the inspection image acquisition unit 3 based on the position information of the part inspected with the preset first luminance and the position information of the part inspected with the aforementioned second luminance. The part to be inspected in P1 (for example, part Ra with low reflectance) and the part to be inspected in the second level inspection image P2 (for example, part Rb with high reflectance) are synthesized into one inspection image Pz Imager. Specifically, the examination image synthesis unit 6 is composed of a processing unit or an image processing unit of a computer CP and an execution program.

Furthermore, in the reference image registration part 4, the following structure is set, that is: Based on the position information of the part checked with the first luminance and the position information of the part checked with the first luminance, the part checked with the first luminance in the first level reference image Pf1 (in this example, the part with low reflectance The part Ra) is synthesized into one image with the part inspected by the second luminance (in this example, the part Rb with high reflectance) in the second level reference image Pf2, and registered as the reference image Pfz. With such a configuration, the reference images Pfz can be collectively managed as one. In this way, not only the number of pre-registered images (that is, the storage capacity) can be reduced, but also the visibility is excellent, which is preferable. In addition, although the process of combining the obtained first level inspection image P1 and second level inspection image P2 into one inspection image Pz is added, only one image of the inspection image Pz and the reference image Pfz It is enough to compare and process each other, and the inspection time will not be greatly delayed as a whole. Therefore, a desired inspection can be quickly performed.

<About the difference in the amount of light in the image> In addition, in the above, as the optical path branching part 2S, the structure provided with the beam splitter which makes a part (for example, 50%) of the light incident from the lower part of the optical path branching part 2S linearly advance, and emits upwards is exemplified. As the first optical path LA, the remaining part (for example, 50%) is reflected and emitted to the right as the second optical path LB. Furthermore, the ND filter 29A is illustrated as having a transmittance of 99% (attenuation rate of 1%), and the filter 29B is illustrated as having a transmittance of 1% (attenuation rate of 99%).

However, the transmittance (attenuation rate) of these ND filters 29A, 29A is only an example after all, and may be appropriately determined according to the brightness (reflectance, transmittance, etc.) of the inspection object.

Moreover, in the above, the configuration including the ND filters 29A and 29B in both the first imaging unit 2A and the second imaging unit 2B was exemplified, but either one (for example, the ND filter 29A) may be omitted. configuration, but only the other (for example, ND filter 29B) configuration.

Alternatively, it is possible to omit the ND filters 29A and 29B by adopting a configuration in which a light quantity difference occurs by dividing the reflectance or the transmittance of the beam splitter. Alternatively, the exposure time (shutter time) of the imaging cameras 26A and 26B or the numerical aperture of the aperture may be set to different conditions respectively.

＜About the number of optical branches＞ In addition, in the above, as the optical path branching unit 2S, the configuration in which the optical axis with respect to the imaging region F is made common and the imaging optical path is branched into two of the first optical path LA and the second optical path LB has been exemplified. This system uses the first imaging unit 2A and the second imaging unit 2B to perform imaging through these branched optical paths.

However, in actualizing the present invention, the number of branches is not limited to two systems, but may be divided into three or more systems. In this case, a third imaging unit or a fourth imaging unit having the same configuration as the first imaging unit 2A or the second imaging unit 2B is configured according to the number of branched optical paths. In this case, the amount of light captured by the first imaging unit 2A, the second imaging unit 2B, and the third imaging unit is 99% (first brightness), 0.9% (second brightness), and 0.09% (third brightness). ,..., etc., pre-set the light branching part 2S or ND filter. Furthermore, the inspection image acquisition unit 3 is configured to obtain the second level inspection image captured at the first brightness by the first imaging unit 2A, and the second level inspection image captured at the second brightness by the second imaging unit 2B. A level inspection image, a third level inspection image captured at a third luminance by a third imaging unit, etc., are obtained at one time as inspection images. Furthermore, in the reference image registration unit 4, the first to third level reference images corresponding to the first to third levels of luminance are provided as inspection references of the first to third level inspection images, etc., and the inspection The unit 5 is configured to perform inspection by comparing the first to third level inspection images and the like with the first to third level reference images and the like.

1: Appearance inspection device 1f: Device frame 2: Camera department 2A: The first camera department 2B: The second camera department 2S: Optical path branch 2L: camera optical path 3: Check the image acquisition part 4: Reference image registration unit 5: Inspection Department 6: Check the image synthesis department 20: lens barrel 22 (22a, 22b): objective lens 23: Spinner 24: Lighting Department 25: half mirror 26A, 26B: camera 27A, 27B: imaging elements 28A, 28B: imaging lens 29A, 29B: ND filter C: Component wafer (chip parts) C: camera department CN:Controller CP: computer F: camera area (field of view) H: Wafer Holder H1: Carrying table L1: lighting light L2: Observation light incident from the wafer side (reflected light, scattered light) LA: 1st light path LB: 2nd light path M: relative movement M1: X-axis slider M2: Y-axis slider M3: rotating mechanism P1: 1st level inspection image P2: Second level inspection image Pf1: 1st level reference image Pf2: Second level reference image Pfz: synthesized reference image Pz: synthesized inspection image Ra: parts with low reflectivity Rb: part with high reflectivity Rx: inspection object part s1～s7, s11～s17: steps Vs: Arrow W: Wafer X1, X2: Defects X, Y, Z, θ: direction ΔP1, ΔP2: Brightness difference (difference)

FIG. 1 is an image diagram showing an example of an inspection image of an example of an embodiment of the present invention. Fig. 2 is a conceptual diagram showing a state of a photographed appearance image of an example of an embodiment of the present invention. Fig. 3(a), (b) is an image diagram showing an example of an inspection image of an example of an embodiment of the present invention. Fig. 4(a), (b) is an image diagram showing an example of a reference image of an example of an embodiment of the present invention. Fig. 5(a), (b) is a conceptual diagram showing an example of an inspection result of an example of an embodiment of the present invention. Fig. 6(a), (b) is a flowchart showing an example of an inspection flow of an example of an embodiment of the present invention. 7( a ), ( b ) are image diagrams showing an example of a reference image of another example of an embodiment of the present invention. Fig. 8 is an image diagram showing an example of an inspection image of the prior art.

1: Appearance inspection device

1f: Device frame

2: Camera department

2A: The first camera department

2B: The second camera department

2S: Optical path branch

2L: camera optical path

3: Check the image acquisition part

4: Reference image registration part

5: Inspection Department

6: Check the image synthesis department

20: lens barrel

22 (22a, 22b): objective lens

23: Spinner

24: Lighting Department

25: half mirror

26A, 26B: camera

27A, 27B: imaging elements

28A, 28B: imaging lens

29A, 29B: ND filter

CN:Controller

CP: computer

F: camera area (field of view)

H: Wafer Holder

H1: Carrying table

L1: lighting light

L2: Observation light incident from the wafer side (reflected light, scattered light)

LA: 1st light path

LB: 2nd light path

M: relative movement

M1: X-axis slider

M2: Y-axis slider

M3: rotating mechanism

P1: 1st level inspection image

P2: Second level inspection image

Pf1: 1st level reference image

Pf2: Second level reference image

Pfz: synthesized reference image

Pz: synthesized inspection image

Rx: Inspection object part

W: Wafer

X, Y, Z, θ: direction

Claims (4)

An appearance inspection device, which is characterized in that it conducts inspection based on an image obtained by photographing the appearance of a part to be inspected, and has: An inspection image acquisition unit that acquires an image obtained by photographing the appearance of the inspection target part as an inspection image; a reference image registration unit, which registers a reference image as an inspection reference of the aforementioned inspection image; and an inspection unit that performs inspection by comparing the inspection image with the reference image; and The inspection image acquisition unit obtains at least a first level inspection image obtained by photographing the appearance of the inspection target part with a first luminance, and an image of the appearance of the inspection target part with a second luminance different from the first luminance. The second-level inspection image is acquired at one time as the aforementioned inspection image, In the reference image registration unit, a first level reference image corresponding to the first brightness as an inspection reference of the first level inspection image, and a first level reference image as the inspection reference of the second level inspection image are registered as the reference image. The inspection standard of the image and the second level reference image corresponding to the aforementioned second brightness, The inspection unit performs inspection by comparing the first level inspection image with the first level reference image, and performs inspection by comparing the second level inspection image with the second level reference image. The appearance inspection device according to claim 1, which is equipped with an imaging unit that photographs the appearance of the inspection target part, and The aforementioned camera department has: an optical path branching unit that makes the optical axis with respect to the imaging area common, and branches the imaging optical path into at least two systems including the first optical path and the second optical path; a first imaging unit for imaging the imaging region with the first brightness via the first optical path; and a second imaging unit for imaging the imaging region with the second brightness via the second optical path; and The aforementioned inspection image acquisition unit The image captured by the first imaging unit is acquired as the first level inspection image, The image captured by the second imaging unit is acquired as the second level inspection image. The visual inspection device according to claim 1 or 2, wherein the position information of the part inspected by the first brightness among the parts to be inspected is defined in association with the first level reference image, The position information of the part inspected with the second luminance among the parts to be inspected is defined in association with the second level reference image, The aforementioned inspection department Comparing the first level inspection image and the first level reference image with the parts inspected by the first brightness are compared and inspected, The inspection is performed by comparing the second level inspection image with the portion inspected by the second brightness in the second level reference image. The appearance inspection device according to claim 3, which is provided with an inspection image synthesis unit, and the inspection image synthesis unit combines the position information of the part inspected with the aforementioned first luminance and the position information of the part inspected with the aforementioned second luminance. The portion of the first level inspection image that is inspected with the first brightness and the portion of the second level inspection image that is inspected with the second brightness are synthesized into one image as the inspection image, In the aforementioned reference image registration unit, Based on the position information of the part checked with the aforementioned first brightness and the position information of the part checked with the aforementioned second brightness, the part checked with the aforementioned first brightness in the aforementioned first level reference image and the aforementioned second level reference The part of the image that was inspected by the aforementioned second brightness is synthesized into one image, and registered as the aforementioned reference image.

Images