JPH1068615A - Appearance inspection system for peripheral part of through hole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system for inspecting the appearance on the periphery of a through hole in which the burden on the eyes of an inspector is lessened and the inspection time is shortened while eliminating fluctuation in the inspection results. SOLUTION: The system for inspecting the appearance on the periphery of a through hole comprises a horizontal inspection table 1 for mounting an object 2 having a through hole 2a, an inspection head 4 movable relatively to the inspection table in two axial directions intersecting perpendicularly in a horizontal plane, an image pickup unit 8 fixed thereto having optical axis vertical to the inspection table, an illuminator 9 built in the lens-barrel 8a thereof and projecting a light beam coaxially therewith, a peripheral illuminator 10 fixed to the outer circumference of the lens-barrel and projecting a light beam to the inspection table at a required inclination angle, a unit 11 for determining GO/NO-GO by comparing an image from the image pickup unit with a reference image, and a controller 14 for controlling the operation of the inspection table according to a predetermined procedure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external appearance inspection apparatus for inspecting the appearance such as chipping and chipping of the periphery of a through hole such as a cathode electrode and a focus ring used for dry etching of a semiconductor wafer.

[0002]

2. Description of the Related Art Reactive ion etching (RIE) for forming a pattern of a semiconductor device on a silicon wafer.
g) The cathode electrode 31 used in the step is, as shown in FIG.
A large number of through-holes 33 are provided in the center part of the second unit 2 and a plurality of mounting holes (not shown) are provided in the peripheral part. The peripheral part of the surface (the upper surface in FIG. It has an arc shape. In the above-mentioned RIE step, the cathode electrode 31 is disposed, for example, above a semiconductor wafer having an insulating layer or a conductor layer formed on the surface thereof.
The reactant gas such as freon is caused to flow downward, that is, toward the wafer surface from the large number of through holes 33, and is used for selectively etching the insulating layer or the conductive layer. Therefore, generation of particles from the cathode electrode 31,
The drop has a significant effect on the yield of semiconductor wafer production, and it is desired that the cathode electrode 31 has as few structural defects as possible factors such as particles from the initial stage. Therefore, as shown in FIG. 13, usually, it is necessary to inspect the periphery of the through hole 33 for the presence or absence of the chip 34 and the chipping 35, or the appearance inspection of the diameter and the position of the through hole 33.
Conventionally, the appearance inspection such as chipping or chipping around the through hole 33 of the cathode electrode 31 is performed using an appearance inspection apparatus shown in FIG. This visual inspection device is mounted on a gantry 36 and is a cathode electrode 3 which is an inspection object having a through hole.
1 is mounted on an inspection table 37 on which the first and the like are placed, and on a gate-shaped moving frame 39 which can be moved horizontally by being guided by a guide rail 38 on a gantry 36, and can be moved in a horizontal direction orthogonal to the moving direction of the moving frame 39 Inspection head 40,
The optical axis is attached to the inspection head 40 and the inspection table 3
An imaging device 41 such as a CCD camera perpendicular to the imaging device 7 and an inspection table 37 attached to the outer periphery of a lens barrel of the imaging device 41.
Peripheral illumination device 4 that projects a light beam with a required inclination angle
2 and a display device 43 for displaying an image by the imaging device 41
And the inspection head 40, the imaging device 41, and the peripheral illumination device 4
And an operation panel 44 for operating the second and the like. Then, the through-hole 3 of the cathode electrode 31 is measured by the above-described visual inspection device.
3 In order to inspect the appearance of the peripheral part, after placing the cathode electrode 31 on the inspection table 37, the operation button of the operation panel 44 is operated to move the inspection head 40 appropriately, and the imaging device 41 will be inspected. Is moved above the through-hole 33 to capture an image of the periphery of the through-hole 33 by the imaging device 41. Do.

[0003]

However, in the conventional visual inspection device for the peripheral portion of the through-hole, the visual inspection of the peripheral portion of the through-hole, such as chipping or chipping, is carried out by visually inspecting the image displayed on the display device. Since the inspection is performed, the burden on the eyes of the inspector is very large, and the time required for the inspection is long, and the judgment criteria for each inspector are different, so that there is a problem that the inspection results vary. Therefore, an object of the present invention is to provide a visual inspection apparatus for a peripheral portion of a through-hole which can reduce a burden on an inspector's eyes, shorten an inspection time, and eliminate variations in inspection results.

[0004]

According to a first aspect of the present invention, there is provided a visual inspection apparatus for a peripheral portion of a through hole, which comprises: a horizontal inspection table for placing an inspection object having a through hole;
2 placed above the inspection table and orthogonal to each other in the horizontal plane
An inspection head movable relative to the inspection table in the axial direction, an imaging device attached to the inspection head, the optical axis of which is perpendicular to the inspection table, and a built-in lens barrel of the imaging device;
An illumination device that projects light rays coaxial with the lens barrel, a peripheral illumination device that is attached to the outer periphery of the lens barrel of the imaging device, and projects light beams at a required inclination angle with respect to the inspection table, and an image input from the imaging device. A determination device for comparing the quality of an inspection object by comparing with a previously input reference image, and a procedure in which the operations of an inspection table or an inspection head, an imaging device, a lighting device, a peripheral lighting device, and a determination device are determined in advance. And a control device for controlling according to the following. The peripheral illumination device includes a hollow annular plate-shaped casing fitted to the outer periphery of the lower end of the lens barrel of the imaging device, and a number of light sources disposed in the casing at a required inclination angle pointing toward the center thereof. Is preferred. Preferably, the inspection table is rotatable about a vertical axis.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an example of an embodiment of a visual inspection device for a peripheral portion of a through hole according to the present invention. In the figure, reference numeral 1 denotes a horizontal inspection table on which an inspection object 2 having a through hole 2a, for example, an RIE cathode electrode or a focus ring made of silicon or glassy carbon is placed. It is installed in. Above the inspection table 1, an inspection head 4 is arranged so as to be movable in two orthogonal (X, Y axis) directions in a horizontal plane. That is, the X-axis driving device 5
There is an upright frame 6 with the bottom mounted.
The X-axis driving device 5 is provided with a Y-axis driving device 7 that is reciprocated in the X-axis direction by the X-axis driving device 5 and that reciprocates the inspection head 4 in the Y-axis direction. An imaging device 8 such as a CCD camera whose optical axis is perpendicular to the inspection table 1 is attached to the inspection head 4, and a lens barrel 8a of the imaging device 8 has a lens barrel 8a as shown in FIGS. A half mirror 9a disposed in the lens barrel 8a for projecting a light beam coaxial with the lens barrel 8a, and a guide cylinder 9b attached to the lens barrel 8a so as to face the half mirror 9a.
A lighting device 9 including a light source 9c such as an LED disposed at the outer end of the guide tube 9b is built in. Also, the imaging device 8
As shown in FIGS. 4 and 5, around the lower end of the lens barrel 8a,
A hollow annular plate-shaped casing 10a fitted on the outer periphery of the lower end of the lens barrel 8a for projecting a ray having the required inclination angle θ to the inspection table 1, and a required inclination angle pointing the center of the casing 10a. A peripheral lighting device 10 including a large number of light sources 10b such as LEDs arranged in the above. The above-mentioned required inclination angle is, for example, an angle smaller than an R-shaped taper angle formed at the peripheral portion of the surface of the through-hole in the case of the through-hole of the RIE cathode electrode. °, more preferably 15 to 25 °. Then, the image obtained by the imaging device 8 is input to the determination device 11, and is compared with a reference image input in advance to the determination device 11 to discriminate the presence or absence of chipping or chipping around the through hole 2 a of the inspection object 2. And the quality of the appearance is determined,
The determination result and / or the image obtained by the imaging device 8 is displayed on the display device 12. X, Y for driving the inspection head 4
Axis driving devices 5 and 7, imaging device 8, coaxial epi-illumination device 9,
The operations of the peripheral lighting device 10, the determination device 11, the display device 12, and the like are controlled by the control device 14 based on a command from the personal computer 13.
Is controlled according to a predetermined procedure.

In order to inspect the appearance of the periphery of the through hole 2a of the inspection object 2 by the appearance inspection device for the periphery of the through hole having the above-described configuration, first, the inspection object 2 is placed on the inspection table 1. Thereafter, a command to start the inspection is issued from the personal computer 13. Based on this command, the control device 14 drives the X and Y axis driving devices 5 and 7 in accordance with a predetermined procedure and
Is moved to position the imaging device 8 above the through hole 2a to be inspected, and then the light source 10b of the peripheral illumination device 10 is turned on to cause the imaging device 8 to perform imaging. At the time of this imaging, the light beam projected from the peripheral illumination device 10 forms a required inclination angle with the inspection table 1, that is, the inspection object 2, as shown in FIG. The light beam hitting the peripheral flat portion proceeds in a direction different from the entrance of the lens barrel 8a, and only the light beam hitting a part of the periphery of the round through-hole 2a enters the lens barrel 8a. Therefore, when there is no chipping or chipping at a part of the periphery of the through hole 2a having a round shape, a white ring-shaped image is obtained as shown in FIG. As shown in FIG. 8, a white ring-shaped image having a shadow imitating chipping, chipping, or the like is obtained. Next, the light source 10b of the peripheral illumination device 10 is turned off, and the coaxial incident illumination device 9 is turned off.
The light source 9c is turned on to cause the imaging device 8 to perform imaging. At the time of this imaging, the light beam projected from the coaxial epi-illumination device 9 is perpendicular to the inspection object 2 as shown in FIG. The light beam that hits the lens barrel 8a travels in a different direction from the entrance of the lens barrel 8a, and only the light beam that hits the flat portion around the through hole 2a
And the other parts darken. Therefore, when there is no chipping or chipping in the peripheral flat portion of the through hole 2a, a black circular image is obtained as shown in FIG.
When there is chipping or chipping, as shown in FIG. 11, a black circular image with a shadow imitating the chipping or chipping added to the periphery is obtained. Each image from the imaging device 8 is input to the display device 12 to be displayed, and is input to the determination device 11 to be determined.
The determination result is input to the display device 12, displayed, and stored in the storage device. In the above description, a case has been described in which appearance inspection such as chipping or chipping of the peripheral portion of the through hole 2a and the flat portion around the through hole 2a is performed. An appearance inspection may be performed.

[0007] According to the appearance inspection apparatus for the periphery of the through hole having the above-described structure, the appearance inspection is automatically performed based on a certain standard, so that the burden on the inspector can be remarkably reduced. In addition, the inspection time can be greatly reduced, and variations in the inspection results can be eliminated.

[0008] In both embodiments described above,
Although the case where the inspection table 1 is mounted on the gantry 3 and the inspection head 4 can be moved in two horizontal axis directions has been described,
The invention is not limited to this, and the inspection head 4 may be fixed and the inspection table 1 may be movable in two horizontal axis directions. Further, the present invention is not limited to the case where the interval between the inspection table 1 and the inspection head 4 is fixed, and may be provided so that the two can be relatively approached and separated. Further, the inspection table 1 may be rotatable about a vertical axis at the center thereof, or the imaging device 8 may be two units having different magnifications. Furthermore, three or more imaging devices 8 having different magnifications may be used.

[0009]

As described above, according to the appearance inspection apparatus for the periphery of a through-hole according to the present invention, the appearance inspection such as chipping, chipping, diameter and position of the periphery of the through-hole is automatically performed based on a certain standard. In this way, the burden on the eyes of the inspector can be significantly reduced, the inspection time can be significantly reduced, and the variation in the inspection results can be eliminated.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of an embodiment of a visual inspection device for a peripheral portion of a through hole according to the present invention.

FIG. 2 is a plan view of a coaxial epi-illumination device in the appearance inspection device of FIG.

FIG. 3 is a sectional view of the coaxial epi-illumination device of FIG. 2;

FIG. 4 is a plan view of a peripheral illumination device in the appearance inspection device of FIG. 1;

5 is a cross-sectional view of the peripheral lighting device of FIG.

FIG. 6 is an explanatory diagram showing an operation of the peripheral lighting device of FIG. 4;

FIG. 7 is a favorable image obtained by the imaging device of the inspection object onto which light rays are projected from the peripheral illumination device of FIG. 4;

8 is a poor image obtained by the imaging device of the inspection target on which light rays are projected from the peripheral illumination device of FIG. 4;

FIG. 9 is an explanatory view showing an operation of the coaxial epi-illumination device of FIG. 2;

FIG. 10 is a good image obtained by the imaging device of the inspection target on which light rays are projected from the coaxial epi-illumination device of FIG. 2;

FIG. 11 is a poor image obtained by the imaging device of the inspection object onto which light rays are projected from the coaxial epi-illumination device of FIG. 2;

FIG. 12 is a perspective view showing an example of an inspection object having a through hole.

FIG. 13 is a partially enlarged view of the inspection object in FIG. 14;

FIG. 14 is a perspective view of a conventional visual inspection device for the periphery of a through hole.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 inspection table 2 inspection object 2a through hole 4 inspection head 8 imaging device 8a lens barrel 9 lighting device 10 peripheral lighting device 11 judgment device 12 display device 14 control device

Claims (3)

[Claims] 1. A horizontal inspection table on which an inspection object having a through hole is placed, and an inspection arranged above the inspection table and movable relative to the inspection table in two axial directions orthogonal to each other in a horizontal plane. A head, an imaging device attached to the inspection head, the optical axis of which is perpendicular to the inspection table, an illumination device built in the lens barrel of the imaging device, and projecting light rays coaxial with the lens barrel, and a lens barrel of the imaging device A peripheral illumination device that is attached to the outer periphery of the device and projects a light beam having a required inclination angle with respect to the inspection table, and compares the image input from the imaging device with a previously input reference image to determine whether the inspection object is good or bad. And a control device for controlling the operation of the inspection table or inspection head, the imaging device, the illumination device, the peripheral illumination device, and the determination device in accordance with a predetermined procedure. Outside Visual inspection equipment. 2. A casing in the shape of a hollow circular plate in which the peripheral illumination device is fitted to the outer periphery of the lower end of a lens barrel of an image pickup device, and a number of light sources disposed in the casing at a required inclination angle pointing toward the center thereof. The visual inspection device for a peripheral portion of a through hole according to claim 1, wherein: 3. The visual inspection apparatus according to claim 1, wherein the inspection table is rotatable about a vertical axis.