JPH0610820B2 - Solid-state imaging device for pattern recognition - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a solid-state image pickup device for pattern recognition, and more particularly to an arrangement shape of pixels thereof.

[Technical background of the invention]

Conventionally, as shown in FIG. 1, a pixel 1 ...
A pattern recognition device using area sensors arranged in a two-dimensional manner is used, for example, in manufacturing a semiconductor device. If a silicon wafer is taken as an example of the subject, a notch portion called an orientation flat is usually formed on the wafer so that the crystal orientation can be identified. Then, the above-mentioned cutout portion is detected by pattern recognition (the hatched portion in FIG. 1 shows an example of the wafer image 2 on the imaging surface of the area sensor formed by the imaging optical system).
Then, the wafer is moved so that the notch is aligned with the reference position. In particular, the pattern recognition in the process of exposing the integrated circuit pattern on the wafer is performed by the displacement information (d, θ) of the center position A of the wafer image 2 at the x, y coordinates (reference coordinates) shown in FIG. It is necessary to detect the direction information of the cutout portion 2 '. In this case, the conventional pattern recognition apparatus is configured to temporarily store the imaged output of the area sensor in the image memory, read the stored data, and perform the arithmetic processing for pattern recognition.

[Problems of background technology]

However, the conventional pattern recognition device as described above requires an area sensor having a large number of pixels and an image memory having a large storage capacity, and thus the system price becomes expensive. In other words, considering the ratio between the pattern recognition ability of the subject and the price, it is effective when the subject pattern is unknown, but when the subject pattern is known, the above capacity-to-price ratio is necessary. The sushi is not good either.

Further, since the above-mentioned conventional device uses the area sensor, the time required for reading the output signal, writing and reading the image memory, and arithmetic processing becomes long, which makes it difficult to speed up pattern recognition. Moreover, since the amount of data for arithmetic processing is large, the configuration of the arithmetic circuit and its peripheral circuits becomes complicated and expensive.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and when the subject pattern is known, pattern imaging for simplifying and accelerating the recognition process of the displacement amount of the subject pattern image with respect to the reference coordinates is possible. A solid-state imaging device for pattern recognition, which can reduce the system price of the pattern recognition device and speed up the recognition process.

[Outline of Invention]

In the solid-state imaging device for pattern recognition of the present invention, N pixels are annularly arranged so as to have substantially the same shape as the peripheral portion of the known subject pattern, and the peripheral portion of the subject pattern image is formed by the imaging optical system. An image pickup surface configured to form an image on N pixels, and means for sequentially reading a signal corresponding to the incident light intensity at each pixel from the first pixel to the Nth pixel in time series. It is equipped with. Then, the first recognition for recognizing the direction of the displacement of the subject with respect to the reference coordinates by the discrimination processing of the position of the pixel showing the minimum signal level and the position of the pixel showing the maximum signal level in the signal output pattern read in time series. Means, second recognizing means for recognizing the amount of displacement of the object with respect to the reference coordinates by calculating the difference between the minimum signal level and the maximum signal level in the signal output pattern read in time series, It is characterized by comprising a third recognition means for recognizing the position of the peculiar shape portion of the subject on the reference coordinates by the discrimination processing of the position of the pixel showing the peculiar pattern in the read signal output pattern.

In the solid-state imaging device for pattern recognition having the above configuration, the signal corresponding to the incident light intensity in each pixel is sequentially read in time series from the first pixel to the Nth pixel, and is read in this time series. The displacement amount of the subject with respect to the reference coordinates can be recognized based on the signal output pattern,
It is possible to grasp the above-mentioned displacement amount by outputting the signal once. Moreover, since the pixels are arranged in a ring shape, the number of pixels used can be reduced. Therefore, it is possible to perform pattern imaging that can simplify and speed up the recognition processing system, reduce the system cost of the pattern recognition device, and speed up the recognition processing.

Example of Invention

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2 shows the arrangement of the pixels (photoelectric conversion elements) P _{1 to} P _{N on} the image pickup surface of the solid-state image pickup device, and corresponds to the case where the subject is, for example, a silicon wafer, the pattern of the peripheral portion (known One-dimensionally arranged so as to have almost the same shape (in this example, an annular shape). The image pickup surface is arranged on the image pickup surface of an image pickup optical system (not shown) so that a pattern image of a subject is formed at a predetermined magnification or scale. In this case, the peripheral portion (indicated by diagonal lines in the figure) 21 of the subject pattern image is imaged on each of the pixels P _{1 to} P _N.

Further, the pixel P ₁ to P _N signal output means (not shown charge transfer register, such as a charge-voltage converting circuit) for reading a signal corresponding to each of the incident light intensity in time series in the order of the pixels P ₁ to P _N are It is provided. Therefore, a one-dimensional sensor capable of outputting a signal according to the incident light intensity pattern in the length direction of the ring is formed.

Note that, in FIG. 2, it is assumed that an image is captured, for example, in a state where the subject is illuminated from behind, and the subject image peripheral portion 2
1 is imaged as a shadow.

Therefore, in the one-dimensional sensor, the pixels P ₁ to
The signal output level corresponding to P _N corresponds inversely to the size of the shadows on the images P _{1 to} P _N , and has a curved output pattern as shown in FIG. 3, for example. This signal output pattern has reference coordinates (x, y with the origin of the arrangement center of the pixels P _{1 to} P _N ).
These are the coordinates, and the pixels P ₁ and P _N are separated into the first quadrant and the fourth quadrant by the x-axis) and vary depending on the amount d of deviation of the subject image center position A from the quadrant and the direction θ. . The direction θ of this deviation is the minimum signal level Vm.
Can be detected by the identification processing of the position of the pixel Pm that indicates the position and the position of the pixel Pn that indicates the maximum signal level Vn. The amount of deviation d can be detected by subtraction processing of the maximum signal level Vn and the minimum signal level Vm.

Note that FIG. 4 shows an example of a signal output pattern in the case where the center position is not displaced.

The signal output pattern has the characteristics of the pattern of the subject image peripheral portion 21.
If there is a peculiar shape part (a cutout part of the wafer in this example), it has a peculiar pattern part corresponding thereto. Then, the position (angle) of the wafer cutout portion on the reference coordinates can be detected by the pattern recognition processing of the unique pattern portion in the signal output pattern and the identification processing of the corresponding pixel position.

According to the solid-state image pickup device for pattern recognition of the above-described embodiment, the image pickup surface has the pixel group arranged in substantially the same shape as the known subject peripheral portion pattern, and the subject is kept stationary without moving. Even the maximum and minimum levels of the imaging output signal are detected, the maximum and minimum level differences are calculated, and the singular pattern area recognition processing is performed to easily recognize the displacement of the subject image peripheral area with respect to the reference coordinates. It becomes possible to do. Also, the number of pixels used is smaller than that of the conventional area sensor, and the signal output means can be driven and processed in the same manner as in a conventional line sensor in which pixels are linearly arranged, and can be realized at low cost. is there. Moreover, since the memory capacity for temporarily storing the image pickup output signal is small and the configuration of the pattern recognition circuit is simple, the system cost of the pattern recognition device is reduced and the pattern image displacement amount recognition processing is performed at high speed. Can be realized.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, when recognizing the displacement amount of a quadrangle subject pattern, as shown in FIG. It suffices to use a solid-state image pickup device having an image pickup surface in which the pixels P _{1 to} P _N are arranged in the above, and form the image 51 of the peripheral portion of the object on each pixel by an image forming optical system.

〔The invention's effect〕

As described above, according to the solid-state imaging device for pattern recognition of the present invention, when the subject pattern is known, the process of recognizing the displacement amount of the subject pattern image with respect to the reference coordinates on the imaging surface is simplified and speeded up. It is possible to image the pattern, and it is possible to reduce the system price of the pattern recognition device and speed up the recognition process.

[Brief description of drawings]

FIG. 1 is a diagram showing a pixel arrangement of an image pickup surface in a conventional pattern recognition solid-state image pickup device, and FIG. 2 is a diagram showing an example of a pixel arrangement of an image pickup surface in a pattern recognition solid-state image pickup device of the present invention. 3 and 4 respectively show image pickup output signals when the object peripheral edge image formed on the image pickup surface in FIG. 2 is displaced with respect to the reference coordinates and when it is not displaced. FIG. 5 is a waveform diagram showing an example, and FIG. 5 is a diagram showing a pixel arrangement on an image pickup surface in another embodiment of the device of the present invention. P _{1 to} P _N ... Pixels, 21, 51 ... Peripheral part of subject image.

Claims (1)

[Claims] 1. N pixels are arranged in an annular shape so as to have substantially the same shape as the peripheral portion of a known subject pattern, and the peripheral portion of the subject pattern image is placed on the N pixels by an imaging optical system. An image pickup surface configured to form an image; a unit that sequentially reads in time series a signal corresponding to the intensity of incident light in each pixel from the first pixel to the Nth pixel; First recognizing means for recognizing the direction of the displacement of the object with respect to the reference coordinates by the identification processing of the position of the pixel showing the minimum signal level and the position of the pixel showing the maximum signal level in the read signal output pattern; Secondly recognizing the amount of deviation of the object with respect to the reference coordinates by calculating the difference between the minimum signal level and the maximum signal level in the signal output pattern read out in series.
And a third recognizing means for recognizing the position of the peculiar shape part of the subject on the reference coordinates by the discrimination process of the position of the pixel indicating the peculiar pattern in the signal output pattern read in time series. And a solid-state imaging device for pattern recognition, comprising: