JPH02307048A - Inspection device for wafer outward apperance - Google Patents

Abstract

PURPOSE:To input pattern images of a reference area and an inspection area and to compare and inspect the patterns without any complicate adjustments by switching the optical paths of the reference area and inspection area by a changeover mirror. CONSTITUTION:This inspection device is provided with an XY stage 7 which can moves in an X-Y direction while mounting a wafer 6, objectives 5a and 5b which input the two image patterns, shutters 4a, and 4b, half-mirrors 3a and 3b, and the changeover mirror 3 which switches the two image patterns. Then when the pattern image of the reference area is inputted, the reference-side shutter 4a is opened and the light from a light source 1 is converged on the reference area 4b of the wafer 6 through the objective 5a. Further, when the pattern image of the inspection area is inputted, the inspection-side shutter 4b is opened and the light from the light source 1 is converged on the inspection area of the wafer 6 through the objective 5b. The switched image patterns are photographed by a CCD camera 9 and the image patterns which are inputted to the camera 9 is converted by a processor 10 into a binary signal, which is stored in a computer 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wafer visual inspection apparatus, and particularly to a pattern matching type wafer visual inspection apparatus.

[Conventional technology]

Conventionally, there are two types of automatic wafer visual inspection apparatuses using this type of pattern matching method. One is a set of optical systems and a camera, and the X
This method captures images of the reference area and inspection area by moving the Y stage.

The other method uses two sets of optical systems and two cameras to simultaneously capture images of the reference area and inspection area without moving the XY stage.

[Problem to be solved by the invention]

Among the conventional wafer visual inspection devices mentioned above, the former
After capturing the image of the reference area, move it to the inspection area
Since the Y stage must be moved to capture an image of the inspection area, there is a drawback that the inspection time becomes longer.

In the latter case, the inspection time is shortened, but the adjustment is complicated because the characteristics of the two cameras must be matched, and when there is a multilayer pattern with multiple brain levels. When inspecting wafers,
There is a problem that testing cannot be carried out. An object of the present invention is to provide a wafer visual inspection apparatus that solves this problem.

[Means to solve the problem]

The automatic wafer appearance inspection apparatus of the present invention includes one CCD camera for photographing a pattern image, one objective lens, one shutter, and one half mirror for capturing images of a reference area and an inspection area.

The apparatus includes a mirror and a switching mirror that switches the optical path between the reference area and the inspection area.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of a wafer visual inspection apparatus showing an embodiment of the present invention. As shown in the figure, this wafer visual inspection system has a wafer 6 mounted thereon, an XY stage 7 that can move in the XY directions, and two sets of objectives that reflect light onto two areas of the wafer surface and capture two image patterns. A lens, a shutter, a half mirror, a switching mirror 3 for switching between these two image patterns, a CCD camera 9 for photographing the switched image pattern, and a digitalization of the image pattern words exposed by the CCD camera 9. The computer 11 includes an image processor 10 and a computer 11 that compare two image patterns.

Next, the operation of this wafer visual inspection apparatus will be explained. First, when capturing a reference area (area) pattern image, open the shutter 4a on the reference side, and open the shutter 4b on the inspection side.
Close. Next, the light emitted from the halogen light source 1a on the reference side is adjusted to an optimal amount by an ND filter 2a, passes through a half mirror 3a and an open shutter 4a, and is directed to the wafer 6 by an objective lens 5a. The light is focused on the reference area. The pattern image by the reflected light from the reference area is again transmitted to the objective lens 5a, shutter 4a and half mirror 3.
a, is refracted by the mirror 8a and the switching mirror 3,
The image is taken into the CCD camera 9. The image pattern captured by the CCD camera 9 is binarized by an image processor 10 and stored in a computer 11.

Next, in order to capture a pattern image of the inspection area, the shutter 4a on the reference side is closed and the shutter 4b on the inspection side is opened. Next, the light emitted from the halogen light source 1b is N-D
Adjusted to the optimum amount with filter 2b, half mirror 3b
and the objective lens 5b through the open shutter 4b.
The light is focused on the inspection area. The pattern image of the target inspection area passes through the objective lens 5b, shutter 4b, and inspection side half mirror 3b again, is refracted by the mirror 8b and the switching mirror 3 switched to the inspection area side, and is taken into the CCD camera 9. The image pattern captured by the CCD camera 9 is binarized by the image processor 10, and compared with the binarized data of the pattern image of the reference area by the computer 11 to detect pattern defects, foreign objects, etc.

FIG. 2 is a block diagram of a wafer visual inspection apparatus showing another embodiment of the present invention. This wafer visual inspection equipment is
The halogen light source was reduced to one, and the light source was shared. The rest is the same as the previous embodiment.

In this embodiment, since the halogen light sources 1 are combined into one, there is an advantage that there is no need to match the two halogen light sources 1a and 1b as in the case of the previous embodiment.

〔Effect of the invention〕

As explained above, the wafer visual inspection apparatus of the present invention includes one for taking a pattern image, a CCD camera, and 41 objective lenses, shutters, half mirrors, and mirrors for capturing images of a reference area and an inspection area. By providing a switching mirror that switches the optical path between the reference area and the inspection area, there is no need to move the X-Y stage, and the pattern between the reference area and inspection area can be changed without the need for complicated adjustments such as matching the characteristics of the camera. This has the advantage that images can be captured and comparative inspection of patterns can be performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a wafer visual inspection apparatus showing one embodiment of the present invention, and FIG. 2 is a block diagram of a wafer visual inspection apparatus showing another embodiment. 1, 1a, 1b=--halogen light source, 2
a, 2b...ND filter, 3...Switching mirror, 3a, 3b...Half mirror, 4a,
4b...Shutter, 5a. 5b...Objective lens, 6...Wafer,
7...XY stage, 8a, 8b...
Mirror, 9... CCD camera, 10...
- Image processor, 11... computer. Agent Patent Attorney Otoman Uchihara 1 Figure

Claims (1)

[Claims] One CCD camera that takes a pattern image, one objective lens, shutter, half mirror, mirror, and optical path of the reference area and the inspection area to take in each pattern image of the reference area and the inspection area. A wafer appearance inspection device characterized by comprising a switching mirror for switching.