JPH10123060A - Apparatus for defect inspection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inspect a defect on a sample by a method in which the sample is irradiated with light in a sufficient quantity without irregularity and uniformly. SOLUTION: By a line-fiber irradiation device 1, a sample 6 is irradiated with flat light along one plane, reflected light from the sample 6 is guided to a line CCD camera 9, and a defect is detected. By a cylindrical line 3, component light in the x-axis direction out of the flat light from the line-fiber irradiation device 1 is focused on the sample 6, and component light in the y-axis direction is defocused on the sample 6. The sample 6 is irradiated with the defocused light uniformly and without irregularity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect inspection apparatus for inspecting the surface of a relatively large specimen such as a large diameter wafer or a large liquid crystal substrate.

[0002]

2. Description of the Related Art A line fiber illuminator for illuminating a specimen with linear light is used for inspecting the surface of a specimen such as a large diameter wafer or a large liquid crystal substrate. Japanese Patent Application Laid-Open No. 6-1849
2 and JP-A-6-31857.

A defect inspection apparatus disclosed in Japanese Patent Application Laid-Open No. 6-18492 illuminates a sample in a line shape with a line fiber illuminator, and captures reflected light from the sample with a line CCD camera. In this apparatus, a line CCD camera is arranged at a position different from the direction of specular reflection light from a line fiber illuminator, and a light shielding member for blocking specular reflection light from the line fiber illuminator incident on the line CCD camera is provided. I have. The light-blocking member reduces the influence of specular reflection on the lens surface of the line CCD camera and the effect of multiple reflections from the sample, thereby detecting only scattered light from defects in the sample. .

The inspection apparatus disclosed in Japanese Patent Application Laid-Open No. 6-311857 has a structure in which an objective lens moves with respect to a specimen. That is, when observing by the transmission illumination method, a line fiber illuminator is arranged in a straight line along the direction in which the objective lens moves, and the specimen is transmitted and illuminated by the line fiber illuminator, thereby moving the objective lens. The specimen can be inspected without moving the condenser lens for transmitted illumination synchronously.

[0005]

Problems to be Solved by the Invention
The apparatus disclosed in Japanese Patent Publication No. 18492 has a problem that the amount of illumination on the specimen becomes uneven due to the emitted light beam from each of the optical fibers focused in the line fiber illumination apparatus, which adversely affects the inspection result. Since the sample is arranged at the defocus position of the line fiber illuminating device to reduce the non-uniformity of the light amount, there is a problem that a sufficient illumination light amount for inspecting the sample cannot be obtained.

In the apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 6-311857, a scattering plate is inserted between a line fiber illumination device and a sample, and the sample is uniformly illuminated by the scattering plate without unevenness. There is a problem that the amount of illumination decreases due to the insertion of the light.

According to the present invention, a sample is illuminated using a line fiber illuminating device, and even in a device for detecting reflected light from the sample, the sample can be uniformly illuminated without reducing the amount of light without unevenness. An object of the present invention is to provide a defect inspection device.

[0008]

In order to achieve the above object, a first aspect of the present invention is to provide a line fiber illuminator for irradiating a sample with flat light along one plane, and a method for reflecting light applied to the sample. Detecting means for detecting a defect on the surface of the sample from the light, a device for moving the irradiation spot irradiated on the sample relative to the sample, the flat light from the line fiber illumination device Among them, the line fiber illumination device and the sample are provided with a light adjusting member that focuses light of a component in a specific axis direction on the sample while guiding light of a component in a direction different from the specific axis direction to the sample in a non-focused state and illuminates the sample. And is disposed between the two.

In this device, the light from the line fiber illuminating device is condensed on the sample, and the reflected light at the illuminated portion on the sample is detected, whereby the defect of the sample can be detected and the illumination on the sample can be performed. Since the portion is moved relatively to the specimen, the entire specimen can be inspected.

[0010] The light adjusting member focuses light of a component in a specific axis direction out of the flat light from the line fiber illuminating device along one plane to the sample, and inspects the defect by using the component light. Light of an axial component different from the axial direction is guided to the sample in an unfocused state, and the sample is illuminated. The illumination by the defocused light averages outgoing light flux from each optical fiber of the line fiber illumination device. Therefore, uniform illumination without unevenness can be performed.

According to a second aspect of the present invention, the line fiber illumination device irradiates the sample obliquely, and the reflected light from the sample is also reflected obliquely. For this reason, all reflected light can be used for defect inspection, and inspection without loss of light quantity can be performed.

According to a third aspect of the present invention, an optical member having an image forming characteristic for making the light in the longitudinal direction out of the flat light and focusing the light in the short direction is used as the light adjusting member. Thus, only the light component in the longitudinal direction is defocused, and the sample can be uniformly and uniformly illuminated by the defocused light component.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 is a perspective view of Embodiment 1, and FIG. 2 is an optical path diagram showing a path of light from a line fiber illumination device. The line fiber illumination device 1 forms a flat light beam along one plane in the y direction, and this light beam passes through a cylindrical lens 2 as a light adjusting member. The cylindrical lens 2 is an optical lens having different optical characteristics between its x-axis and y-axis. In other words, only the light component dispersed in the x-axis direction is focused on the sample 6 with respect to the light traveling direction, while the light component dispersed in the y-axis direction is guided to the sample 6 in an unfocused state. doing. The light that has passed through the cylindrical lens 2 is appropriately focused by the condenser lens 3 and passes through the half mirror 4. The light that has passed through the half mirror 4 is focused on the specimen 6 by the objective lens 5 to form a linear illumination spot 7.

The reflected light from the sample 6 is again reflected on the objective lens 5.
And enters the half mirror 4. Here, the reflected light is reflected by the half mirror 4 on the basis of the reflectance, and the remaining light is transmitted. The light reflected by the half mirror 4 further passes through the detection lens 8. The reflected light is converged by the detecting lens 8 and received by a line CCD camera 9 as a detecting means. The line CCD camera 9 has CCD elements arranged linearly in the y-axis direction, and can capture reflected light from the sample 6 at one time in the y-axis direction. Then, the entire surface of the specimen 6 can be inspected by moving the linear illumination spot 7 illuminating the specimen 6 relative to the specimen 6 in the x direction.

FIGS. 2 (a) and 2 (b) show the light emitted from the line fiber illuminating device 1 until the light illuminating spot 7 on the specimen 6 is irradiated with respect to the y-axis and the light traveling direction. x
The axis is shown. Of the light emitted from the line fiber illuminating device 1, the light spreading in the x-axis direction is shown in FIG.
As shown in (1), the light is converged to some extent by the cylindrical lens 2, passes through the condenser lens 3 and the objective lens 5, and forms an image at the focal position Fx. On the other hand, of the light emitted from the line fiber illuminating device 1, the light that spreads in the y-axis direction is not converged even after passing through the cylindrical lens 2 as shown in FIG. And passes through the objective lens 5 to form an image at a position Fy farther than the focal position Fx.

Accordingly, when the specimen 6 is arranged at the focal position Fx, the illumination location 7 is focused and illuminated with light expanding in the x-axis direction, but is defocused with respect to light expanding in the y-axis direction. Illuminated. For this reason, the light beams emitted from the line fiber illumination device 1 are defocused with respect to the y-axis and overlap each other on the focal position Fx. As a result, in the illuminated area 7, a sufficient illumination light amount is obtained by the focused illumination light in the x-axis direction, and uniform illumination is performed by the defocused illumination light in the y-axis direction. That is, at the illumination location 7, the light component in only the y-axis direction is defocused. Therefore, the amount of illumination light is remarkably different from that in the conventional case where the light is defocused in all directions on the sample. It will not drop.

(Second Embodiment) FIG. 3 shows a second embodiment. In this embodiment, the line fiber lighting device 1 is
It is arranged and illuminated in an oblique direction with respect to the specimen 6. A flat light ray formed by the line fiber illuminating device 1 along one plane in the y direction passes through the cylindrical lens 2. After passing through the condenser lens 3,
The light is focused on the specimen 6 to form a linear illumination spot 7.

The reflected light from the illuminated spot 7 on the specimen 6 is focused by the detecting lens 8 and received by the line CCD camera 9. The line CCD camera 9 captures light from the illuminated spot 7 on the specimen 6 and moves the illuminated spot 7 relative to the specimen 6 in the x direction to inspect the entire surface of the specimen 6 for defects. Can be.

In this embodiment, the sample 6 is illuminated by disposing the line fiber illuminating device 1 in a direction oblique to the sample 6. Thereby, the optical axis of the emitted light emitted from the line fiber illumination device 1 and the optical axis of the reflected light from the illumination location 7 can be different axes, and the half mirror 4 that separates the emitted light and the reflected light can be used. It becomes unnecessary. Accordingly, it is possible to prevent a decrease in the amount of light emitted from the line fiber illuminating device 1 and reflected light from the illuminated portion 7 generated by the half mirror 4, and to guide a more sufficient amount of light to the line CCD camera 9. .

(Embodiment 3) FIGS. 4 and 5 show Embodiment 3 in which a diffraction grating 10 is used as a method for defocusing only a light component in the y-axis direction at an illumination location 7 on a specimen 6. FIG. ing. FIGS. 4A and 4B are similar to FIG.
FIG. 3 is an optical path diagram showing the y-axis and the x-axis with respect to the direction in which light travels until light emitted from the line fiber illumination device 1 is irradiated on a sample 6 as an illumination location 7. Of the light emitted from the line fiber illuminator 1, the light that spreads in the x-axis direction passes through the diffraction grating 10 as shown in FIG. 4, passes through the condenser lens 3 and the objective lens 5, and forms an image at the focal position Fx. .

As shown in FIG. 5, the diffraction grating 10 is provided with a myriad of slits 11 extending in the x-axis direction in the y-direction. Accordingly, of the light incident on the diffraction grating 10, y
The light polarized in the direction is diffracted by the slit 11,
Separate in each direction and go straight.

Of the light emitted from the line fiber illuminating device 1, the light that spreads in the y-axis direction is converted by the diffraction grating 10 into a large number of separated light beams emitted in a predetermined direction. The light beams separated in these directions pass through the condenser lens 3 and the objective lens 5 and reach the focal point Fx. The light that spreads in the y-axis direction in this manner is
And overlap on the focal point Fx. Therefore, when the sample 6 is arranged on the focal point Fx, a sufficient illumination light amount can be obtained by the illumination light focused in the x-axis direction, and
Uniform illumination is provided by the defocused illumination light in the y-axis direction.

In the above embodiment, the light component in the x-axis direction is focused and the light component in the y-axis direction is defocused.
The light component in the axial direction may be focused.

The present invention described above also includes the following inventions. (1) A line fiber illuminator that irradiates a sample with flat light along one plane, and a detection unit that detects a defect on the surface of the sample from reflected light of light applied to the sample, and irradiates the sample. A device that relatively moves the irradiated portion with respect to the sample, and among the flat light from the line fiber illuminating device, while focusing light of a component in a specific axis direction on the sample, A light adjusting member for guiding light of a component in a direction different from that to the sample in an unfocused state and illuminating the sample is arranged between the line fiber illuminating device and the sample, and the adjusting member is provided with a longitudinal light source for the flat light. It is a cylindrical lens extending along the direction. (2) In the above (1), the light adjusting member is a diffraction grating in which a slit extends along a lateral direction of the flat light.

[0025]

As described above, according to the present invention, light in a specific axis direction is focused by a light adjusting member such as a cylindrical lens or a diffraction grating, and light in a direction different from the specific axis direction is defocused so that a specimen is unfocused. Since the illumination is performed, the sample can be uniformly and uniformly illuminated without a decrease in the amount of light.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment.

FIGS. 2A and 2B are optical path diagrams of the first embodiment.

FIG. 3 is a perspective view of a second embodiment.

FIGS. 4A and 4B are optical path diagrams according to a third embodiment.

FIG. 5 is a front view of a diffraction grating.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Line fiber illumination device 2 Cylindrical lens 3 Condenser lens 4 Half mirror 5 Objective lens 6 Sample 7 Illumination spot 8 Detection lens 9 Line CCD camera 10 Diffraction grating 11 Slit

Claims (3)

[Claims] 1. A specimen comprising: a line fiber illuminator for irradiating a flat light along a plane onto a specimen; and detecting means for detecting a defect on the surface of the specimen from reflected light of the light applied to the specimen. A device for moving an irradiation spot irradiated relative to a sample relative to the sample, of the flat light from the line fiber illumination device, while focusing light of a component in a specific axis direction to the sample, A defect inspection apparatus, wherein a light adjusting member for guiding light of a component in a direction different from the axial direction to the sample in a non-focusing state and illuminating the sample is arranged between the line fiber illumination device and the sample. 2. The defect inspection device according to claim 1, wherein the line fiber illumination device irradiates the sample with oblique light obliquely. 3. The light adjusting member according to claim 1, wherein the light adjusting member is an optical member that brings the light in the longitudinal direction out of the flat light into a non-focusing state and focuses the light in the short-side direction. 2. The defect inspection apparatus according to item 2.