JPH0795038B2 - Object defect inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a defect inspection apparatus for an object that optically inspects a short-circuit defect state of a Nesa film electrode, for example.

(Prior Art) As an apparatus for optically inspecting a defect existing in an object, an inspection apparatus shown in FIG. 4 is known. That is, reference numeral 1 denotes a laser oscillator, and a laser beam L oscillated from the laser oscillator 1 is scanned by a beam scanner 2 composed of a galvanometer mirror, and the scanning light is condensed by a condenser lens 3 to be on the surface of the object 4. A scanning optical system 5 for irradiating is provided. Further, the light passing through the object 4, that is, the scattered beam generated from the object 4 is detected by the detection optical system 6 or the detector 7 distant from the beam axis. The detection optical system 6 includes relay lenses 8, 9,
It is composed of a mask 10 and a detector 11, forms an image of the beam scanner 2 at the position of the mask 10, cuts off an unscattered beam passing through the object 4 by the mask 10, and an image of the object 4 by the relay lenses 8 and 9. It is made in the detector 11 to detect this.

Using the object defect inspection apparatus configured as described above,
As shown in the figure, when inspecting the short-circuit defect state of the Nesa film electrode, the laser beam L is scanned on the surface of the Nesa film electrode 12 ...
Can be detected by 11.

(Problems to be Solved by the Invention) However, in the case of inspecting the defects 14 of the Nesa film electrodes 12 ... Using the defect inspection device configured as described above, there are the following problems. That is, the Nesa film electrodes 12 ... Usually have a width of about 450 μm and are insulated from each other by the insulating portions 13 of about 65 μm. Reference numeral 14 is a defect existing in the Nesa film electrode 12, which is short-circuited across the insulating portion 13. Even if such a defect 14 is to be inspected by the inspection device, since the nesa film electrode 12 has a uniform thickness, the scattered beam is weak and the SN ratio of the signal is poor. Therefore, if the scanning beam is narrowed down in order to increase the sensitivity, dust existing on the surface of the nesa film electrode 12 causes a scattered beam, and the dust and the defect 14 cannot be distinguished, and the defect detection reliability is poor. There is. Further, when the detection optical system 6 as described above is scanned with a beam, the image of the object 4 on the detector 11 changes, so that the detector 11 needs to be upsized, which complicates the configuration. There is.

The present invention has been made in view of the above circumstances, and an object thereof is to be able to reliably detect only defects in which an object exists, improve the reliability of inspection, and configure An object of the present invention is to provide a device for inspecting an object, which can simplify the above.

(Means and Actions for Solving Problems) The present invention is directed to a condensing lens for condensing a laser beam into a spot diameter as large as a defect to be detected by a scanning optical system and a beam for scanning on an object. A scanner, a mask for blocking light that has passed through the object without scattering the detection optical system, and a slit for transmitting only a scattered beam to the detector and a slit in front of the beam scanner and the slit in the scanning plane. Consists of a lens that has a focus and is perpendicular to the scanning surface and the object and the slit in front of the detector, so that only defects can be detected without being affected by dust existing on the object. It is configured in.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the first embodiment and shows a state in which it is applied to a transmission type inspection apparatus. A is a scanning optical system, and B is a detection optical system. First, the scanning optical system A will be described. Reference numeral 21 is a laser oscillator. The laser beam L oscillated from the laser oscillator 21 is reflected by the mirror 22 and guided to the beam scanner 23 composed of a galvanometer mirror. Then, the beam scanner 23 scans the laser beam L. A condenser lens 24 is provided on the optical axis of this scanning beam.
Has a focal point aligned with the scanning axis of the beam scanner 13 and is arranged so as to focus light on an object 25 such as a Nesa film electrode, which is an object to be inspected, with a predetermined spot diameter D described later. Next, the detection optical system B will be explained.
Is an elongated mask having a width equal to or larger than the spot diameter D scanned by the beam scanner 23, and is installed behind the object 25. A lens 27 focusing on the object 25 is provided further behind the mask 26, and a cylindrical lens 2 is provided behind the lens 27.
8, slit 29 and detector 30 are installed. The focus position of the lens 27 on the detector 30 side is on the slit 29 in the lens 27 alone, but the slit 29 is the beam scanner.
It is parallel to the scanning plane of the scanning beam given by 23 and is in a position corresponding to the image by the scanning axis of the beam scanner 23 and both optical systems A and B. With respect to the surface perpendicular to the scanning surface, the slit 29 is in image correspondence with the surface of the object 25 by the detection optical system B due to the effect of the cylindrical lens 28. The cylindrical lens 28 has its axis aligned with a plane perpendicular to the scanning plane, and its focal point is on the slit 29. Further, the detector 30 is a photoelectric conversion element located immediately after the slit 29, and this detector 30 amplifies this output signal.
The signal is amplified by 31 and input to a comparator 32, where it is connected to an electric circuit 33 that obtains a detection signal by comparing with a comparison signal s.

The spot diameter D of the scanning beam condensed by the condenser lens 24 of the scanning optical system A is set so that dust existing on the object 25 is not detected. That is, the size of ordinary dust is several microns, and the intensity of the scattered beam due to this dust increases in proportion to the ratio between the diameter of dust and the spot diameter corresponding to it. Therefore, the Nesa film electrode 12
The signal from the defect 14 is made stronger than the dust signal by increasing the ratio of the spot diameter D to the defect 14 by adjusting the spot diameter D to the size of the defect 14 short-circuited across the insulating portion 13. There is. That is, the spot diameter D of the scanning beam was set to about 450 μm, which is the width of the Nesa film electrode 12.

Next, the operation of the object inspection apparatus configured as described above will be described. The laser beam L oscillated from the laser oscillator 21 is scanned by the beam scanner 23 so as to be contained in the condenser lens 24, and is refracted by the condenser lens 24 so as to be scanned in parallel. The focused beam focused by the focusing lens 24 is projected onto the object 25. Since the spot diameter D on the object 25 is focused on the specific defect size (about 450 microns) on the object 25 as described above,
Sensitivity decreases for dust smaller than this size. on the other hand,
Since the detection optical system B is arranged so that the scanning axis of the beam scanner 23 and the slit 29 correspond to the image, the beam is one point on the slit 29 and is always stationary. Further, since the object 25 and the slit 29 are adapted to correspond to images on the surface perpendicular to the scanning surface, the scattered beam from the object 25 is condensed on the slit 29. Thus the slit 29 is an object
Only the width of the beam scattered by 25, which is perpendicular to the scanning plane, and which is focused on the optical axis by the lens 27 and the cylindrical lens 28 is selected, and the other light is cut off. As a result, the maximum value of the scattered beam from the object 25 can be guided to one detector 30 at one point. The signal from the detector 30 is amplified by the amplifier 31, and then the comparator 32 compares the level with the comparison signal s. When the level of the input signal is higher than that of the comparison signal, the signal is output from the comparator 32. As a result, only the defect of the desired level can be obtained as the detection signal.

FIG. 2 and FIG. 3 show a second embodiment and show a state in which the reflection type inspection apparatus is implemented. The basic configurations of the scanning optical system A and the detection optical system B are the same as those of the transmissive type. This embodiment is applied to a liquid crystal panel inspection, and the focused beam focused on the surface 25a of the object 25 made of a glass substrate becomes the surface reflected light 34 as shown by the solid line, passes through the object 25 and the back surface. The back surface reflected light 35 reflected by 25b enters the detection optical system B as shown by the broken line. In this case, since the central axis of the scattered beam reflected by the defect 36 existing on the back surface 25b of the object 25 is in a direction different from that of the surface 25a, this can be blocked by the slit 29, and like the first embodiment. object
Only the scattered beam scattered by 25 will be focused on the slit 29.

〔The invention's effect〕

As described above, according to the present invention, by making the spot diameter of the focused beam to be scanned on the object comparable to the size of a specific defect existing on the object, dust and scratches on the object are affected. It is possible to reliably detect only defects without being damaged. Moreover, since the detector receives light at one point, it is not affected by the sensitivity distribution, so that a uniform signal can be obtained, and the size can be reduced.

[Brief description of drawings]

1 is a block diagram of a defect inspection apparatus showing a first embodiment of the present invention, FIG. 2 is a block diagram of a defect inspection apparatus showing a second embodiment of the present invention, and FIG. FIG. 4 is an enlarged explanatory diagram, FIG. 4 is a configuration diagram of a conventional defect inspection apparatus, and FIG. 5 is an explanatory diagram showing a defect state existing in the Nesa film electrode. A ... Scanning optical system, B ... Detection optical system, 23 ... Beam scanner, 24 ... Condensing lens, 25 ... Object, 26 ... Mask, 27 ... Lens, 28 ... Cylindrical lens, 29 ...
… Slits, 30 …… detectors, 33 …… electric circuits.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 62-219631 (JP, A) JP 62-124447 (JP, A) JP 53-136881 (JP, A) JP 62- 274248 (JP, A) JP 62-228149 (JP, A) JP 62-220842 (JP, A)

Claims (2)

[Claims] 1. A defect inspection apparatus for an object, comprising: a scanning optical system for scanning a laser beam on the object; and a detection optical system for detecting light passing through the object to inspect defects existing on the object. The scanning optical system includes a condensing lens that condenses a laser beam into a spot diameter approximately the same size as a defect to be detected, and a beam scanner that scans the laser beam on the object, The optical system, a mask that blocks the light that has passed through the object without being scattered, a slit that transmits only a scattered beam to the detector, and a slit provided between the slit and the mask, on the scanning surface of the beam scanner, A beam scanner and an optical system having a focus on the slit in front of the detector, and an optical system having a focus on the object and the slit in front of the detector on a plane perpendicular to the scanning plane. It said detector defect inspection apparatus of an object, characterized by comprising an electric circuit for obtaining a defect detection signal by comparing the comparison signal a signal obtained from the detector is. 2. The defect inspection apparatus for an object according to claim 1, wherein the detection optical system detects a transmitted beam or a reflected beam from the object.