Image analysis – Applications – Manufacturing or product inspection
Reexamination Certificate
1997-08-08
2001-12-04
Ahmed, Samir (Department: 2623)
Image analysis
Applications
Manufacturing or product inspection
C382S209000
Reexamination Certificate
active
06327379
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pattern inspection method and apparatus, and, in particular, to an inspection method and apparatus of a circuit pattern with an auxiliary pattern. The circuit pattern is a circuit pattern formed in a mask or the like and used in manufacturing of a semiconductor device.
Recently, high-density integration of semiconductor devices has been developed. As a result, circuit patterns has become finer. As shown in
FIG. 1
, when using a mask of a pattern of rectangles
10
and performing an exposure, a pattern
11
is formed on a wafer. Due to limitations of resolution of an exposure device, as pattern becomes finer, the rounded pattern shapes
11
occur. When such a phenomenon occurs in a circuit pattern, the corners are rounded. As a result, although electrical connection is performed, it is likely that problems in circuit characteristics will occur.
In order to solve this problem, that is, in order to form a circuit pattern according to design, as shown in
FIG. 2
, a technique of adding an auxiliary pattern
12
has been used. The auxiliary pattern
12
includes small rectangles, each of which is positioned near a respective corner of the rectangles of the pattern
10
. As a result of adding the auxiliary pattern
12
, a pattern
13
formed on a wafer is approximately rectangular.
In order to perform inspection as to whether or not defects are present in a circuit pattern including an auxiliary pattern, a pattern inspection method which considers the presence of the auxiliary pattern is needed.
2. Description of the Related Art
Up to this time, inspection of a circuit pattern including an auxiliary pattern has been performed by the same method as that for an ordinary circuit pattern not including an auxiliary pattern. Specifically, as shown in
FIG. 3
, an image of a pattern of a mask is recognized in a process
20
. Thereby, a recognized image
23
including a pattern image
21
and an auxiliary pattern image
22
is obtained. On the other hand, design data including the auxiliary pattern is copied in a process
25
. Then, in a process
26
, the design data is converted into inspection data which is suitable for conducting inspection of the circuit. Then, in a process
27
, the inspection data is converted into an image, and thus, an inspection image
28
including a pattern image
21
A and a auxiliary image
22
A is obtained. In a process
29
, the recognized image
23
is compared with the inspection image
28
, and thus, it is determined whether or not defects are present in a circuit pattern of the mask.
The design data which is converted in the process
26
is design data including the auxiliary pattern. The amount of data of this design data is several times larger than the amount of data of the ordinary design data not including the auxiliary pattern. As a circuit pattern becomes finer as mentioned above, the amount of data of the ordinary design data not including the auxiliary pattern increases. Accordingly, the amount of data of the design data including the auxiliary pattern is enormous. As a result, a very long time is required for the data conversion in the process
26
, and thus, a very long time is required for the pattern inspection.
Further, due to limitation of data processing capability of the pattern inspection apparatus, as a circuit pattern becomes finer, the petter inspection is performed by dividing one mask into a plurality of divisions and data processing is performed. In such a situation, because the amount of data increases when design data including the auxiliary pattern is processed as mentioned above, it is necessary to divide one mask into an increasing number of divisions. Thereby, a longer time is required for the pattern inspection.
Further, because each rectangle of the auxiliary pattern is very small in comparison to the ordinary pattern, the auxiliary pattern may result in false defects in the pattern inspection. Thus, reliability of the pattern inspection is degraded.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a pattern inspection method and apparatus in which the above-described problems are solved.
In a pattern inspection according to the present invention:
an actual pattern image including an auxiliary pattern in a periphery of a pattern of an object to be inspected is recognized;
the image of the auxiliary pattern is deleted from the recognized image and an auxiliary-pattern-image-deleted recognized image is produced;
an inspection image to be used for inspection is produced from design data from which the auxiliary pattern is removed; and
the auxiliary-pattern-image-deleted recognized image is compared with the inspection image.
In this arrangement, an image, obtained from deleting an auxiliary pattern image from a pattern image which includes the auxiliary pattern in a periphery of a pattern, is inspected. Therefore, an image to be compared with the above-mentioned image is an image which is produced from design data from which the auxiliary pattern has been removed. The amount of data of the design data without the auxiliary pattern is very small in comparison to the design data with the auxiliary pattern. Accordingly, a time required for producing the inspection image from the design data can be decreased. Thereby, a time required for the inspection of the object to be inspected can be decreased. Thus, efficiency of the pattern inspection can be improved. Further, because the comparison is performed on the images without the auxiliary patterns, occurrence of false defects is reduced. Thereby, the inspection of the circuit pattern of the mask is performed with high accuracy, and reliability of the inspection can be improved.
In another pattern inspection according to the present invention:
A picture of one position of an object to be inspected is taken through a first optical system, and an actual pattern image including an auxiliary pattern in a periphery of a pattern is recognized.
The image of the auxiliary pattern is deleted from this recognized image, and a first auxiliary-pattern-image-deleted recognized image is produced.
A picture of another position, which corresponds to the one position, of an object to be inspected, is taken through a first optical system, and an actual pattern image including an auxiliary pattern in a periphery of a pattern is recognized.
The image of the auxiliary pattern is deleted from this recognized image, and a second auxiliary-pattern-image-deleted recognized image is produced.
The first auxiliary-pattern-image-deleted recognized image is compared with the second auxiliary-pattern-image-deleted recognized image.
In this arrangement, the first auxiliary-pattern-image-deleted recognized image is compared with the second auxiliary-pattern-image-deleted recognized image. As a result, because the comparison is performed on the images without the auxiliary patterns, occurrence of false defects is reduced. Thereby, the inspection of the circuit pattern of the mask is performed with high accuracy, and reliability of the inspection can be improved.
Other objects and further features of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.
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patent: 4532650 (1985-07-01), Wihl et al.
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patent: 5568566 (1996-10-01), Hori et al.
patent: 1-248616 (1989-10-01), None
patent: 5-027409 (1993-02-01), None
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Kobayashi Ken-ichi
Matsuyama Takayoshi
Ahmed Samir
Armstrong, Westerman, Hattori, McLeland & Naughton, LLP.
Fujitsu Limited
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