TWI458966B - Pattern inspecting method, and pattern inspecting device - Google Patents

Description

Pattern inspection method and pattern inspection device

The present invention relates to a pattern inspection method for inspecting a pattern formed on a substrate or the like, a pattern inspection device, and a camera for a pattern inspection device.

In order to inspect the pattern of a substrate having a fine pattern like a plasma display panel or a liquid crystal, the pattern inspection device of Fig. 14 has been conventionally used.

This pattern inspection device is configured to take in the pattern D of the inspection object 63 by the camera 66 composed of the camera 64 and the optical lens system 65. The control unit 67 controls the distance between the optical lens system 65 and the imaging element 68 based on the signal obtained by the imaging element 68 of the camera 64.

This conventional pattern inspection device detects a defect of the pattern D of the inspection object 63 by processing the digital data of the pattern D taken in by the camera 64. A representative processing method is to compare the data of the pattern D without defects with the data of the object 63 to be taken in by the camera 66 to find the pattern D defect. Although this method is simple in processing, there is a problem that the magnification of the imaging system is uncertain and the data is difficult.

In order to overcome this problem, there is a method of adjacency comparison: comparing the data of the object 63 to be inspected by the camera 66 with the pattern before or after a few cycles or a few cycles, and finding a portion that is not periodic, and determining it as a defect. This is a method in which the pattern D of the inspection object 63 is periodic.

Further, when a CMOS element, a CCD element, or a MOS element is used as the image pickup element 68, there is a case where the element size of the image pickup element 68 and the pattern pitch of the inspection object 63 are not suitable to cause a measurement error.

As a method of eliminating this measurement error, there is a method described in Patent Document 1. The method described in Patent Document 1 is a method in which a pattern obtained by an optical lens system is projected on a solid-state image sensor with a minimum detection defect size as a unit size, and an integer number of units are included in one pitch. In the mode, the control unit 67 sets the magnification of the optical lens system.

However, even in the method described in Patent Document 1, it takes time to inspect a finer pattern over a large area, and a lot of cost is required for inspection. Therefore, generally, the following method is employed in which a plurality of imaging units are used as the camera, and the area of the object to be inspected is divided so as to capture the pattern in a short time. Here, each imaging unit has a camera and an optical lens system provided between the object to be inspected and the camera.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] JP-A-2003-329609

For example, when a plurality of imaging units are used as in the method described in Patent Document 1, a plurality of imaging units are mounted on one gantry, and the inspection apparatuses are simplified as compared with all of them.

However, if a plurality of imaging units are mounted on one gantry, it is necessary to individually focus the plurality of imaging units on the surface of one object to be inspected. In other words, each of the image pickup units requires a drive unit for moving the respective image pickup units independently (in the Z-axis direction) with respect to the inspection object.

The present invention has been made in view of the above problems, and an object of the invention is to provide a pattern inspection method, a pattern inspection device, and a camera for a pattern inspection device which can realize a configuration in which a plurality of imaging units are in focus.

A pattern inspection device according to the present invention for solving the above-described problems includes a camera in which a scanning pattern is arranged side by side on a surface of an object to be inspected, and an image pickup device and an optical lens system unit are mounted thereon, and a control device is spaced apart from each other. The pattern inspection device is characterized in that the camera has a driving portion that causes the gantry to which the plurality of image pickup units are fixed to approach the exiting direction with respect to the surface of the object to be inspected. The imaging unit is configured by an imaging element unit having an imaging element and an optical lens system unit that is movable in the approaching and separating direction. The control device causes the magnification of the optical lens system unit to be in the following range. The optical lens system unit moves, and the focus of each of the imaging units is aligned on the surface of the object to be inspected, and the defect of the pattern is detected.

C(N-ΔN)/P<M<C(N+ΔN)/P

Here, C: the element pitch of the imaging element, P: the pitch of the pattern, N: the number of elements of the imaging element in the projection image pitch of the pattern, and ΔN: the permissible element of the projection image.

Further, the camera for a pattern inspection device according to the present invention is configured to photograph a pattern arranged on a surface to be inspected by a plurality of imaging units, and the image pickup device includes a gantry that is movable in a vertical direction with respect to the surface to be inspected. And a plurality of imaging units mounted on the gantry, wherein the imaging unit is composed of an imaging element and an optical lens system unit movable in the vertical direction.

Further, in the pattern inspection method of the present invention, the pattern of the surface of the object to be inspected is periodically arranged by scanning with the image pickup unit on which the image pickup device and the optical lens system unit are mounted, and the defect of the pattern is checked in comparison with a portion separated by a predetermined period. This method is characterized in that the optical lens system unit is moved such that the magnification of the optical lens system unit is within the following range, and the focus of each of the imaging units is aligned with the surface of the inspection object, and then the detection is performed. Defects of the aforementioned pattern.

C(N-ΔN)/P<M<C(N+ΔN)/P

Here, C: the element pitch of the imaging element, P: the pitch of the pattern, N: the number of elements of the imaging element in the projection image pitch of the pattern, and ΔN: the permissible element of the projection image.

According to the present invention, it is possible to provide a pattern inspection method, a pattern inspection device, and a camera for a pattern inspection device which can realize a configuration in which a plurality of imaging units are in focus.

Hereinafter, each embodiment of the present invention will be described with reference to Figs. 1 to 13 .

(Embodiment 1)

Fig. 1 is a schematic block diagram showing a configuration and a principle of a camera used in a pattern inspecting apparatus according to a first embodiment of the present invention.

This camera 100 is used to read the pattern 3 formed on the surface of the object 2 to be placed on the mobile station 1. The camera 100 has three imaging units 5a, 5b, and 5c fixed to the gantry 4.

Further, the inspection object 2 is a substrate of a display panel such as a plasma display panel or a liquid crystal panel. More specifically, the display panel is attached to the gap between the front panel and the back panel. In the case of a plasma display panel, the space inside is divided into discharge areas of respective display colors. In the case of a liquid crystal panel, the space inside is filled with liquid crystal. The aforementioned pattern 3 is formed on the front panel or the back panel, and the pattern of the front panel or the back panel before the bonding is inspected.

The control device 6 adjusts the imaging units 5a, 5b, and 5c so that the object 2 can be imaged while the focus is on the pattern 3. This control device 6 executes the assembly adjustment flowchart shown in FIG. 3 at the time of assembly, which will be described in detail later.

The imaging unit 5a is composed of an imaging element 7a and an optical lens system unit 8a. The optical lens system unit 8a is disposed between the imaging element 7a and the object 2 to be inspected, and is in a direction close to the direction of the surface of the object 2 to be inspected ( Hereinafter, it is referred to as moving vertically in the Z-axis direction.

The imaging unit 5b is composed of an imaging element 7b and an optical lens system unit 8b. The optical lens system unit 8b is disposed between the imaging element 7b and the inspection object 2, and is vertically movable in the Z-axis direction.

The imaging unit 5c is composed of an imaging element 7c and an optical lens system unit 8c. The optical lens system unit 8c is disposed between the imaging element 7c and the inspection object 2, and is vertically movable in the Z-axis direction.

In addition, for the sake of simplicity, only the minimum necessary components are described in FIG.

Meanwhile, in order to obtain necessary reading characteristics, the optical lens system units 8a, 8b, and 8c also have a structure of a plurality of lens groups or a structure using an aspherical lens or the like. The drawing omits a drive system for moving the optical lens system unit 8a, 8b, 8c, or a control device for controlling the drive.

As the imaging elements 7a, 7b, and 7c, a solid-state imaging element of a semiconductor such as a CMOS element, a CCD element, or a MOS element is used. Among these elements, there are a linear type or a regional type, but in the present invention, either a straight type or a regional type can be used.

By the relative movement of the inspection object 2 and the gantry 4, each of the image pickup units 5a, 5b, and 5c attached to the gantry 4 scans the allocated area of the inspection object 2 to read the pattern 3. In the present embodiment, the inspection object 2 and the gantry 4 are relatively moved in the direction perpendicular to the paper surface of FIG. 1, and the X-axis direction of the inspection object 2 is scanned.

2(a), 2(b), and 2(c) are diagrams each showing a specific example of Fig. 1.

Both sides of the gantry 4 are slidably supported in the Z-axis direction with respect to the surface of the inspection object 2 in a state of being positioned by the guides 9a, 9b. The main shaft 10 mounted on the fixed table 12 drives the screw shaft 11 screwed to the screw hole formed on the gantry 4 to rotate, and the drive gantry 4 slides in the Z-axis direction with respect to the surface of the inspection object 2. Here, the Z-axis drive unit 30 is constituted by the screw shaft 11 and the main motor 10 and the like.

In the gantry 4 disposed along the Y-axis direction orthogonal to the X-axis direction, the imaging element unit 13a having the imaging element 7a, the imaging element unit 13b having the imaging element 7b, and the imaging element unit 13b are fixed in the Y-axis direction at predetermined intervals. The imaging element unit 13c having the imaging element 7c.

Further, on the gantry 4, the optical lens system units 8a, 8b, and 8c are attached so as to be vertically slidable in the Z-axis direction with respect to the surface of the inspection object 2. Further, the optical lens system units 8a, 8b, and 8c are mounted in a state where the optical axis is aligned with the imaging element unit 13a, the imaging element unit 13b, and the imaging element unit 13c.

The optical lens system unit 8a is positioned on one side by a guide 14a extending in the Z-axis direction, and is screwed to a screw hole formed on the other side so that the axis is supported in parallel with the guide 14a. 1 on the screw shaft 15a. The first screw shaft 15a is driven to rotate by the first motor 16a attached to the gantry 4, and the optical lens system unit 8a is driven to slide in the Z-axis direction. Similarly, the second screw shaft 15b is driven to rotate by the second motor 16b attached to the gantry 4, and the optical lens system unit 8b is driven to slide in the Z-axis direction. The third screw shaft 15c is driven to rotate by the third motor 16c attached to the gantry 4, and the optical lens system unit 8c is driven to slide in the Z-axis direction. The optical lens system unit 8b is positioned by the guide 14b, and the optical lens system unit 8c is positioned by the guide 14c.

FIG. 3 shows a flow chart at the time of assembly of the camera 100.

First, in step S1, the imaging units 5a, 5b, and 5c are fixed to the gantry 4 in a state where the position in the vertical direction (Z-axis direction) is aligned with respect to the plane of the inspection object 2. At this time, as shown in FIG. 4, the imaging elements 7a, 7b, and 7c of the imaging units 5a, 5b, and 5c include mounting errors Δz1 and Δz2 of about 100 μm in the Z-axis direction.

In step S2, the main motor 10 is operated to focus the pattern 3 on the imaging unit 5a, and the gantry 4 is moved in the Z-axis direction for adjustment. Here, the state of the in-focus pattern 3 of the image pickup unit 5a is a state in which the focus image of the pattern 3 can be obtained by the image pickup device 7a.

When the focus of the image pickup unit 5a is aligned, the magnification of the image pickup unit 5a is measured at step S3. Then, in step S4, it is determined whether or not the magnification measured at step S3 is a magnification suitable for the pattern.

In the case where it is determined in step S4 that the magnification is not suitable, the magnification of the imaging unit 5a is adjusted in step S5.

The procedure of steps S2, S3, S4, and S5 is repeated to determine whether the magnification is suitable for the pattern. Then, if it is determined in step S4 that the magnification is appropriate, it is determined that the adjustment of the imaging unit 5a is completed. When the adjustment of the image pickup unit 5a is completed, step S6 is performed next.

In step S6, the adjustment is performed so that the image pickup unit 5b and the image pickup unit 5c are in focus. Specifically, first, the second motor 16b is operated to obtain the focus image of the pattern 3 in the imaging element 7b of the imaging unit 5b, and the optical lens system unit 8b is moved in the Z-axis direction. Next, the third motor 16c is operated to obtain the focus image of the pattern 3 in the imaging element 7c of the image pickup unit 5c, and the optical lens system unit 8c is moved in the Z-axis direction.

By adjusting the imaging units 5a, 5b, and 5c in this manner, the mounting errors Δz1 and Δz2 generated by the respective imaging units 5a, 5b, and 5c in step S1 can be repaired. However, in the case where the adjustment is performed in this way, the magnification of the image of each of the image pickup units 5a, 5b, and 5c is subtly different. That is, in the present embodiment, the magnification adjustment of the imaging unit and the focusing of the pattern are performed using the adjustment flow shown in FIG. 3.

Further, the camera of the present embodiment may move only the optical lens system units 8a, 8b, and 8c of the imaging units 5a, 5b, and 5c. In other words, the gantry 4 in which the plurality of imaging units 5a, 5b, and 5c are common is only one driving mechanism that is driven in the Z-axis direction. Therefore, the structure can be simplified as compared with the case where each of the image pickup units is provided with a drive mechanism that is driven in the Z-axis direction. Since the structure is simple, the driving precision of the drive mechanism is good, and the cost of the drive mechanism is also reduced.

Fig. 5 (a) and Fig. 5 (b) are explanatory views showing the configuration and performance of the image pickup unit of the embodiment. Since the configurations of the imaging units 5a, 5b, and 5c are the same, the imaging unit 5b will be described here.

Fig. 5 (a) is a schematic configuration diagram of the image pickup unit 5b. Fig. 5 (b) is a diagram showing the relationship between the amount of movement of the optical lens and the amount of movement of the focus when the distance between the imaging element 7b and the optical lens system unit 8b is changed. In addition, the graph of FIG. 5(b) is a graph in which the optical lens system unit 8b is moved while the image pickup device 7b is fixed, and measurement is performed.

In the present embodiment, 1/F=1/L1+1/L2 and M=L2/L1 of the lens formula satisfy the following conditions:

F: focus distance of the optical lens system unit 8b = 15 mm

L1: distance between the optical lens system unit 8b and the object 2 to be inspected = 20 mm (when the amount of movement is 0)

L2: distance between the optical lens system unit 8b and the imaging element 7b = 60 mm (when the amount of movement is 0)

M: Magnification = 3 (when the movement amount is 0)

In the above relationship, in the case where only the optical lens system unit 8b is moved, the amount of movement of the optical lens is substantially the same as the amount of movement of the focus.

The change in the amount of movement of the optical lens and the magnification is shown in FIG. Further, the amount of change in the stretching/contraction when the 100 μm pattern is projected onto the image pickup element 7b in a projection pattern of 300 μm is shown in FIG.

According to these figures, it can be seen that if the optical lens system unit 8b is moved above 0.1 mm (Z-axis direction), it is known from FIG. 5(b) that the focus moves from the surface of the object 2 in the Z-axis direction. Only about 0.1mm. Further, if the focus is moved by only about 0.1 mm in the Z-axis direction, it is understood from Fig. 7 that the projection pattern of 100 μm is contracted by only about 0.6 μm from 300 μm.

Generally, when the camera 100 is assembled, an installation error of the gantry 4 of about ±50 μm is generated. In the present embodiment, the optical lens system unit 8b can be moved to eliminate the error generated thereby. In addition, even when the optical lens system unit 8b is moved by a maximum of 100 μm for the purpose of elimination, the stretching and contraction of the pattern 3 due to the change in magnification is 0.6 μm with respect to the pattern of 300 μm.

Next, in the present embodiment, it was examined whether or not the pattern was checked. Hereinafter, the influence of 0.6 μm of the 300 μm pattern will be described.

First, the pattern inspection device of the camera 100 described so far will be described.

First, the pattern inspection device scans the pattern periodically arranged on the surface of the planar object to be inspected by the camera 100 to perform digitization. Then, the control device 6 compares the pattern data of the portion separated by a certain period with the manipulated pattern to detect the defect of the pattern.

A method of pattern comparison inspection (hereinafter referred to as a comparison inspection method) of a portion different from the pattern data is also used in the technique described in Patent Document 1. Since the pattern inspection device uses a solid-state image sensor as an image pickup device, when a pitch portion of a pattern is projected on an image pickup device, it is necessary that a pitch portion of the pattern is surely included in an integer number of image pickup units. This is because if a pitch portion of the pattern is not included in an integer number of image pickup units, even when the pattern is compared, even a pattern of one cycle is judged to be different at the edge portion, and erroneous detection occurs. Therefore, the comparative inspection method is to compare and check the data obtained when the magnification of the optical lens system unit is optimized.

Although the magnifications of the imaging units 5a, 5b, and 5c are slightly different for focusing, the camera 100 of the present embodiment satisfies the allowable value of the magnification required for the comparison inspection by the comparison inspection method.

Next, a relationship in which the pattern image of 300 μm on the image sensor 7b of the present embodiment is changed by 0.6 μm in accordance with the magnification change due to focusing will be described with reference to FIG.

As shown in Fig. 8, the imaging element 7b of the present embodiment has a cell size of 10 μm. The pattern 3 of the test object 2 of 100 μm described with reference to Fig. 1 is pattern-projected onto 30 cells having a cell size of 10 μm by the optical lens system unit 8b of the optimum magnification as a projection image 17 of 300 μm.

As shown in Fig. 8, since the cell size of the present embodiment is 10 μm, the shortage of 0.6 μm is 6% with respect to the cell.

In the comparison check method, the detection result is not affected, and the amount of projection of the projection image generated by focusing with respect to the unit can be tolerated by several %. Furthermore, the excess amount of the unit is converted into an allowable range of magnification. It is necessary to determine the amount of movement of the optical lens system unit 8b within the allowable range of this magnification.

In the present embodiment, the tolerance (magnification magnification M) of the magnification of the optical lens system unit 8b of the imaging unit 5b needs to be controlled within the range of the following formula (1).

C(N-ΔN)/P<M<C(N+ΔN)/P ......(1)

Further, C: the element pitch of the image sensor 7b, P: the pitch of the pattern 3, N: the number of elements (integer) of the image sensor 7b in the pitch of the projection image 17, and ΔN: the allowable amount (element) of the projection image 17.

FIG. 9 shows a series of flowcharts until the control device 6 derives the allowable amount of mounting errors of the imaging units 5a, 5b, and 5c.

Here, the element pitch C=10, the pitch P=100, and the number of components N=30. The allowable amount ΔN becomes a unit of the projection pattern that is allowed to exceed a few unit parts.

First, in step S11, the allowable excess of ΔN is determined based on the inspection accuracy required by the object 2 to be inspected or the like. For example, let the allowable excess amount be 6%, that is, ΔN = 0.06 unit parts.

Next, in step S12, the excess allowable amount ΔN is substituted into the above formula (1), and the allowable magnification M is derived. When applied to the example described with reference to Fig. 7, the allowable magnification M is a condition of the following formula (2).

2.994<M<3.006 ......(2)

When the allowable magnification M is derived, the movement allowance amount of the optical lens system units 8b and 8c is determined in step S13.

The relationship between the amount of movement of the optical lens system units 8b, 8c and the magnification depends on the optical design of the image pickup units 5a, 5b, 5c. The movement allowance based on this magnification becomes the mounting error tolerance of each of the image pickup units 5a, 5b, and 5c in step S14.

From this relationship, it is understood that in the present embodiment, the optical lens system units 8b, 8c can be moved to 0.1 mm. Therefore, the focus position can be moved to 0.1 mm, and the mounting error is repaired by ±50 μm, and it can be confirmed that the focus of each of the image pickup units 5a, 5b, and 5c is not affected by the surface of the inspection object 2. That is, it was confirmed that the pattern data obtained by the configuration of the present embodiment is suitable for the comparative inspection method.

The configuration of the imaging unit 5b described above is a basic configuration. However, by optical lens design, a more appropriate structure can be designed. Hereinafter, the conditions of the appropriate configuration will be described using the imaging unit 5b.

First, in the minimum condition of the appropriate configuration of the present embodiment, the image pickup device 7b is fixed, the optical lens system unit 8b is moved, and the image pickup unit 5b is focused. At this time, the magnification of the imaging unit 5b changes due to the change in the distance between the optical lens system unit 8b and the imaging element 7b. However, as described above, the change in the magnification is small to the extent that the comparison inspection method is small, so that it can be focused within the tolerance of the magnification suitable for the comparative inspection method.

As an example of an optical lens design that satisfies such conditions, there is a design in which the distance between the optical lens system unit 8b and the imaging element 7b is longer. It is preferable to design such that the distance between the optical lens system unit 8b and the image pickup element 7b and the distance between the optical lens system unit 8c and the image pickup element 7c are longer even if the respective image pickup units 5a, 5b, and 5c have the same magnification. This is because the distance between the optical lens system unit 8b and the image pickup device 7b, the longer the distance between the optical lens system unit 8c and the image pickup device 7c, and the smaller the change amount of the magnification when the distance between the optical lens system unit 8b and the image pickup device 7b is changed. . In addition, since the amount of change in the magnification when the distance between the optical lens system unit 8c and the imaging element 7c is changed is small, the movement allowable distance of the optical lens system units 8b and 8c within the allowable change in the magnification becomes long.

By designing under such conditions, the mounting error can be repaired even when the mounting accuracy of the image pickup units 5a, 5b, and 5c is not detailed. Further, in the case where it is necessary to further reduce the range of the tolerance of the magnification change, that is, it is necessary to further reduce the magnification error between the image pickup units 5a, 5b, and 5c, it is also possible to cope with such an optical lens design.

Further, the study of the depth of focus of each of the imaging units 5a, 5b, and 5c when the pattern 3 is projected on the imaging elements 7a, 7b, and 7c is also important. That is, although the focus depth is deep, there is no problem of focusing, but the depth of focus depends on the numerical aperture of the optical lens system units 8a, 8b, and 8c, that is, NA. In order to make the projection image when the pattern 3 is projected on the image pickup elements 7a, 7b, and 7c, it is necessary to design the NA of the optical lens system units 8a, 8b, and 8c to be improved.

To increase the NA of the optical lens system unit, it is preferable to design the camera unit to have a shallow depth of focus. This is because although there is no problem of focusing if the depth of focus is deep, the depth of focus is inevitably shallow in order to increase the definition of the projected image. Further, in the case where the depth of focus is deep, since the image is projected as a pattern to the structure behind the pattern, accurate photographing may not be possible. From this point of view, the depth of focus of the camera unit needs to be shallow. In the present embodiment, it is preferable that the depth of focus of the imaging unit is 20 μm or less.

Furthermore, the present invention also has a feature of omitting a drive mechanism that normally drives each image pickup unit, a drive mechanism in the image pickup unit, and the like. Therefore, it is considered that it can be applied to a scanning device or the like that reads a precise image at high speed even if it is not an inspection device.

Further, according to the pattern inspection device, the drive mechanism for driving each image pickup unit or the drive mechanism in the image pickup unit or the like is omitted. Therefore, the pattern inspection device can be manufactured at low cost.

(Embodiment 2)

Fig. 10 (a) is a schematic block diagram showing the configuration and principle of a camera used in the pattern inspection device according to the second embodiment of the present invention. Fig. 10 (b) is an enlarged view of a portion A of Fig. 10 (a).

The camera 200 of the second embodiment reads the pattern 3 formed on the surface of the inspection object 2 placed on the moving table 1.

The gantry 24 is supported to be slidable in the Z-axis direction with respect to the surface of the inspection object 2. The main shaft 10 attached to the fixed table 12 drives the screw shaft 11 that is screwed to the screw hole formed in the gantry 24 to rotate, and the drive gantry 24 slides in the Z-axis direction with respect to the surface of the inspection object 2.

In the present embodiment, four imaging units 25a, 25b, 25c, and 25d are fixed to the gantry 24.

In order to photograph the object 2 in a state in which the focus is on the pattern 3, the image pickup units 25a to 25d have been adjusted at the time of assembling the gantry 24.

The imaging unit 25a is composed of an imaging element unit 26a and an optical lens system unit 28a. The imaging element unit 26a is provided with an imaging element 7a, and is vertically movable in the Z-axis direction with respect to the surface of the inspection object 2. The optical lens system unit 28a is disposed between the imaging element unit 26a and the inspection object 2, and is vertically movable in the Z-axis direction with respect to the surface of the inspection object 2. Further, in the present embodiment, the imaging element unit 26a and the optical lens system unit 28a are connected so as to be one unit by using the driving unit 27a that can adjust the distance therebetween. The imaging element unit 26a and the optical lens system unit 28a are attached to the gantry 24 via the driving unit 27a.

The imaging unit 25b is composed of an imaging element unit 26b and an optical lens system unit 28b. The imaging element unit 26b includes an imaging element 7b that is vertically movable in the Z-axis direction with respect to the surface of the inspection object 2. The optical lens system unit 28b is disposed between the imaging element unit 26b and the inspection object 2, and is vertically movable in the Z-axis direction with respect to the surface of the inspection object 2. The imaging element unit 26b and the optical lens system unit 28b are connected so as to be one unit by the driving unit 27b that can adjust the distance between them. The imaging element unit 26b and the optical lens system unit 28b are attached to the gantry 24 through the driving unit 27b.

The imaging unit 25c is composed of an imaging element unit 26c and an optical lens system unit 28c. The imaging element unit 26c includes an imaging element 7c that is vertically movable in the Z-axis direction with respect to the surface of the inspection object 2. The optical lens system unit 28c is disposed between the imaging element unit 26c and the inspection object 2, and is vertically movable in the Z-axis direction with respect to the surface of the inspection object 2. The imaging element unit 26c and the optical lens system unit 28c are coupled by a driving unit 27c that can adjust the distance between them. The imaging element unit 26c and the optical lens system unit 28c are attached to the gantry 24 through the driving unit 27c.

The imaging unit 25d is composed of an imaging element unit 26d and an optical lens system unit 28d. The imaging element unit 26d includes an imaging element 7d that is vertically movable in the Z-axis direction with respect to the surface of the inspection object 2. The optical lens system unit 28d is disposed between the imaging element unit 26d and the inspection object 2, and is vertically movable in the Z-axis direction with respect to the surface of the inspection object 2. The imaging element unit 26d and the optical lens system unit 28d are coupled by a driving unit 27d that can adjust the distance between them. The imaging element unit 26d and the optical lens system unit 28d are attached to the gantry 24 through the driving unit 27d.

Depending on the optical configuration of the inspection target or the imaging units 25a to 25d, the inclination angle may be required to be high with respect to the inspection target. In this case, as shown in Fig. 10 (b), the imaging units 25a to 25d are provided with an adjustment shaft mechanism 29 between the imaging element units 26a to 26d and the driving units 27a to 27d, and the adjustment shaft mechanism 29 can be positive. The three directions Ro, Pi, and Ya of the rolling-pitch-yaw around the three axes of the intersection are tilt-adjusted.

With such a configuration, the distance between the optical lens system unit 28a and the imaging element 7a can be adjusted by controlling the driving portion 27a by the control device 6. Similarly, by controlling the driving portion 27b by the control device 6, the distance between the optical lens system unit 28b and the imaging element 7b can be adjusted. Similarly, by controlling the driving portion 27c by the control device 6, the distance between the optical lens system unit 28c and the imaging element 7c can be adjusted. Similarly, by controlling the driving portion 27d by the control device 6, the distance between the optical lens system unit 28d and the imaging element 7d can be adjusted. By adjusting the distance between the optical lens system unit and the imaging element, the focal planes of the imaging units 25a to 25d can be adjusted to the same surface, and the imaging units 25a to 25d can be simultaneously moved by the single Z-axis driving unit 25. Here, the Z-axis drive unit 30 is constituted by a screw shaft 11 , a main motor 10 , and the like.

11(a), 11(b), and 11(c) show a specific example of Fig. 10(a).

In a state where the both sides are positioned by the guides 9a and 9b, the gantry 24 disposed along the Y-axis direction is supported to be slidable in the Z-axis direction with respect to the surface of the inspection object 2. The image pickup units 25a to 25d are fixed to the gantry 24 at predetermined intervals in the Y-axis direction.

The image pickup element unit 26a of the image pickup unit 25a is positioned on one side by a guide 34 extending in the Z-axis direction, and is screwed to a screw hole formed on the other side, so that the shaft center is supported by the guide 34. Parallel to the helical shaft 36. The screw shaft 36 is driven to rotate by a motor 38 attached to the gantry 24, and drives the image pickup element unit 26a to slide in the Z-axis direction. The optical lens system unit 28a that makes the optical axis coincide with the imaging element unit 26a is positioned on one side by the guide 35 extending in the Z-axis direction, and is screwed to the screw hole formed on the other side so that the axis It is supported on a screw shaft 37 parallel to the guide 35. The screw shaft 37 is driven to rotate by a motor 39 mounted on the gantry 24, and drives the optical lens system unit 28a to slide in the Z-axis direction.

The case of the imaging units 25b to 25d is also the same as that of the imaging unit 25a. The imaging element unit 26b of the imaging unit 25b is driven to slide in the Z-axis direction by the motor 42 driving the rotary screw shaft 40. The optical lens system unit 28b of the imaging unit 25b is driven to slide in the Z-axis direction by the motor 43 driving the rotary screw shaft 41.

The imaging element unit 26c of the imaging unit 25c is driven to slide in the Z-axis direction by the motor 46 driving the rotary screw shaft 44. The optical lens system unit 28c of the imaging unit 25c is driven to rotate in the Z-axis direction by driving the rotary screw shaft 45 by the motor 47.

The imaging element unit 26d of the imaging unit 25d is driven to slide in the Z-axis direction by the motor 50 driving the rotary screw shaft 48. The optical lens system unit 28d of the imaging unit 25d is driven to slide in the Z-axis direction by the motor 51 driving the rotary screw shaft 49.

(Embodiment 3)

Fig. 12 is a schematic plan view showing a pattern inspecting apparatus according to a third embodiment of the present invention.

In the third embodiment, the gantry 61 corresponding to the gantry 4 of the first embodiment or the gantry 24 of the second embodiment is moved in the Z-axis direction by operating the main motor 10 of the Z-axis driving unit 30. On the gantry 61, a plurality of imaging units are mounted in two rows with the gantry 61 interposed therebetween. Eight imaging units 62a to 62h are attached to the gantry 61 of the present embodiment. Since the specific mounting method is the same as that of the first embodiment or the second embodiment, the description thereof will be omitted.

By mounting a plurality of imaging units on the gantry 61, the inspection area of the inspection object 2 can be divided into two areas. Therefore, the moving distance of the inspection object 2 can be reduced to half the distance of one line. As a result, compared with the configuration of the first embodiment or the second embodiment, the inspection speed is increased, and the inspection time can be shortened.

Fig. 13 shows a modification of the third embodiment.

In the modification of the third embodiment, as in the configuration shown in FIG. 12, the gantry 61 is arranged in a row of eight imaging units 62a, 62c, 62e, and 62g, and imaging units 62b, 62d, 62f, and 62h. 2 lines of another line. In the case where the inspection object 2 is moved in the X-axis direction with respect to the gantry 61 and reading is performed, the imaging unit 62a reads the region E1 of the inspection surface of the inspection object 2, and the imaging unit 62b reads In the region E2 of the inspection surface of the inspection object 2, the imaging unit 62c reads the region E3 of the inspection surface of the inspection object 2, and the imaging unit 62d reads the region E4 of the inspection surface of the inspection object 2. In the same manner, the regions E5, E6, E7, and E8 of the inspection surface of the inspection object 2 are read by the image pickup units 62e, 62f, 62g, and 62h, and the staggered arrangement of the positions of the image pickup units 62a to 62h is shifted. By forming such a configuration, the inspection object 2 can be efficiently inspected with one scan.

As the main motor 10, the first motor 16a, the second motor 16b, the third motor 16c, and the motors 38, 39, 42, 43, 46, 47, 50, 51 of the above-described embodiments, a stepping motor or a servo motor can be used. .

[Industry use possibility]

The present invention can be utilized for pattern inspection of a display panel such as a plasma display panel or a liquid crystal panel.

1. . . Mobile station

2. . . Inspected object

3. . . pattern

4, 24, 61. . . shelf

5a, 5b, 5c, 25a ~ 25d, 62a ~ 62h. . . Camera unit

6. . . Control device

7a~7c. . . Camera element

8a～8c, 28a～28d. . . Optical lens system unit

9a, 9b, 14a, 14b, 14c, 34, 35. . . Guide

10. . . Main motor

11, 36, 37, 40, 41, 44, 45, 48, 49. . . Screw shaft

12. . . Fixed table

13a, 13b, 13c, 26a ~ 26d. . . Camera component unit

15a～15c. . . First to third spiral axes

16a~16c. . . First to third motors

27a~27d. . . Drive department

29. . . Adjusting the shaft mechanism

30. . . Z-axis drive unit

38, 39, 42, 43, 46, 47, 50, 51. . . motor

E1 ~ E8. . . The area of the inspection surface of the inspection object 2

100. . . camera

200. . . camera

Fig. 1 is a schematic configuration diagram of a camera of an inspection apparatus according to Embodiment 1 of the present invention.

2(a) is a schematic front view showing a specific example of FIG. 1, FIG. 2(b) is a schematic side view for showing a specific example of FIG. 1, and FIG. 2(c) is a view for showing the specific example of FIG. The outline of the specific example is shown above.

Fig. 3 is a flow chart showing the assembly adjustment of the camera of the first embodiment.

4 is a schematic block diagram for explaining an installation error of a plurality of cameras.

Fig. 5 (a) is a schematic configuration diagram of an image pickup unit according to the first embodiment, and Fig. 5 (b) is a view showing a relationship between the amount of movement of the optical lens and the amount of focus shift in the first embodiment.

Fig. 6 is a view showing the relationship between the amount of movement of the optical lens of the first embodiment and the magnification.

Fig. 7 is a view showing the relationship between the amount of movement of the optical lens and the amount of change in the projection pattern in the first embodiment.

Fig. 8 is a view showing a relationship between a projection pattern and a unit of an image pickup element according to the first embodiment;

Fig. 9 is a flow chart for deriving the mounting error of the image pickup unit of the first embodiment.

Fig. 10 (a) is a schematic configuration diagram of a camera of an inspection apparatus according to a second embodiment of the present invention, and Fig. 10 (b) is an enlarged view of a main part of the camera of the second embodiment.

Fig. 11 (a) is a schematic front view for showing a specific example of Fig. 10, Fig. 11 (b) is a schematic side view for showing a specific example of Fig. 10 (a), and Fig. 11 (c) is for displaying The schematic top view of the specific example of Fig. 10 (a).

Fig. 12 is a schematic block diagram showing a configuration of a camera according to a third embodiment of the present invention.

Fig. 13 is a schematic block diagram showing a modification of the camera of the third embodiment of the present invention.

Fig. 14 is a schematic view showing a conventional pattern inspection device.

1. . . Mobile station

2. . . Inspected object

3. . . pattern

4. . . shelf

5a. . . Camera unit

5b. . . Camera unit

5c. . . Camera unit

6. . . Control device

7a. . . Camera element

7b. . . Camera element

7c. . . Camera element

8a. . . Optical lens system unit

8b. . . Optical lens system unit

8c. . . Optical lens system unit

100. . . camera

Claims (7)

A pattern inspection device comprising: a camera that scans a pattern periodically arranged on a surface of an object to be inspected, and an imaging element and an optical lens system unit; and a control device that compares portions separated by a certain period In order to check the defect of the pattern, the pattern inspection device is characterized in that the camera has a driving portion that allows the gantry to which the plurality of image pickup units are fixed to move in a direction of approaching and leaving with respect to the surface of the object to be inspected, The imaging unit includes an imaging element unit having an imaging element and an optical lens system unit movable in the approaching and separating direction. The control device causes the optical lens system such that the magnification M of the optical lens system unit is in the following range. The unit moves, and the focus of each imaging unit is aligned on the surface of the object to be inspected in a state in which the magnifications of the respective imaging units are different, and the defect C(N-ΔN)/P<M< of the pattern is detected. C(N+ΔN)/P where C: the component pitch of the image sensor, P: the pitch of the pattern, N: the pattern within the projected image pitch Like elements as the number, △ N: allowable element of the projection image. The pattern inspection device of claim 1, wherein the optical lens system unit has a depth of focus of 20 μm or less. The pattern inspection device of claim 1 or 2, wherein the optical lens system unit is designed to: relative to the light due to the focusing The amount of change in the distance between the lens system unit and the imaging element is reduced, and the amount of change in the magnification becomes small, and the distance between the optical lens system unit and the imaging element becomes long. The pattern inspection device of claim 1 or 2, wherein the imaging unit is separated into two units of an optical lens system unit and an imaging element unit, wherein the imaging unit and the optical lens system unit are in a straight line The driving unit that is driven in the forward direction is coupled, and the control device adjusts the distance between the optical lens system unit and the imaging element unit by controlling the driving unit. The pattern inspection device according to claim 3, wherein the image pickup element unit is attached to the gantry via an adjustment shaft mechanism that adjusts a tilt angle of a focal plane and an object to be inspected. A pattern inspection method for scanning a pattern that is periodically arranged side by side on a surface of an object to be inspected by an image pickup unit equipped with an image pickup element and an optical lens system unit, and comparing the pattern with a portion separated by a predetermined period to check the pattern In the method of the pattern, the optical lens system unit is moved such that the magnification M of the optical lens system unit is within the following range, and each of the imaging units has a different magnification. After the focus of the image pickup unit is aligned with the surface of the object to be inspected, the defect C(N-ΔN)/P<M<C(N+ΔN)/P of the pattern is detected, where C: the component pitch of the image pickup element , P: the spacing of the pattern, N: the number of elements of the image pickup element in the projected image pitch of the pattern, ΔN: the allowable element of the projected image. The pattern inspection method of claim 6, wherein the optical lens system unit is designed to reduce a change in magnification with respect to a change amount of a distance between the optical lens system unit and the image pickup element due to the focusing. And the distance between the optical lens system unit and the imaging element becomes long.