JPH0624037B2 - Pattern inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] In a pattern inspection method of the present invention, a time required for reducing an inspection area to 1 / A according to an image density of the inspection object and performing a scanning process on the reduced inspection object. And the inspection object pattern is inspected while synchronizing with the reduced inspection object A times and synchronizing with the time for image conversion processing of the enlarged inspection data of the inspection object.

As a result, it becomes possible to perform high-speed inspection of the image pattern of the inspection object that is to be highly densified, and reduce the load on the image conversion apparatus.

[Industrial application field]

The present invention relates to a pattern inspection method for a pattern to be inspected, for example, a photomask pattern, and more specifically to a pattern matching inspection technique.

[Conventional technology]

FIG. 2 is a diagram for explaining a pattern inspection method for an inspected pattern according to a conventional example.

In the figure, the actual image of the inspection area 2 of the inspection object 1 is received and processed by the electrical processing means 3. The inspection target 1 is processed by the scanning processing means 11. Next, the electrically processed image data is stored in the memory 4. Next, the inspection pattern 5 of the inspection area 2 is created based on the image data.

Further, the inspection data 6 is processed by the image conversion processing means 7 to create the inspection pattern 8.

Then, the pattern to be inspected 5 and the pattern for inspection 8 are aligned and compared and collated by the comparison and collation means 9, and the inspection result 1
Get 0.

The object 1 to be inspected is an example of a reticle such as a mask of a semiconductor device.

[Problems to be solved by the invention]

By the way, according to the conventional example, in the database inspection in which the pattern to be inspected and the inspection pattern are compared and collated, the image density becomes higher as the semiconductor device is highly integrated and has a higher density.
The image conversion processing time of the inspection data increases, and the processing load on the image conversion processing apparatus increases.

On the other hand, the pattern to be inspected cannot be compared and collated until the pattern for inspection is created, and the adjustment time is overrun. During this time, the displacement of the pattern to be inspected is caused by the vibration of the driving system that performs the scanning process.

For this reason, there is a problem that the inspection pattern cannot be inspected due to a difference between the image conversion processing time and the scanning processing time.

The present invention was created in view of the problems of the conventional example, and an object of the present invention is to provide a pattern inspection method that eliminates the difference between both processing times and enables processing of an image with high density.

[Means for solving problems]

In the pattern inspection method of the present invention, as shown in the embodiment diagram and FIG. 1, the inspection target 21 is scanned by the scan processing means 33 to obtain an image of the inspection target 21, and the image is electrically processed. The processing means 23 performs signal processing, the image data subjected to the signal processing is stored in the storage means 24, and the pattern to be inspected 25 is created from the stored image data, and the image conversion processing means 27 creates from the inspection data 26. In the pattern inspection method for comparing and collating with the reference inspection pattern 28, the image density detecting means 30 of the inspected object 21 detects,
When the image density is high, the inspection area 22 is reduced to 1 / A by the reduction means 32, the inspection data 26 of the inspection object 21 is reduced, and the inspection data 26 is converted into the reference inspection pattern 28. By shortening the time, the image of the inspected object 21 in the reduced inspected area 22 is enlarged A times by the enlarging means 31, and the inspected object 2 is enlarged.
The inspection accuracy of No. 1 is increased, the scanning processing time for acquiring the image of the inspection object 35 enlarged to A times is increased, and the image conversion time and the scanning processing time are matched with each other. Achieve the purpose.

[Action]

According to the present invention, the image density of the inspection object is detected by the detection means 30 and the inspection area according to the image density is reduced, thereby increasing the time for scanning the inspection area of the inspection object. On the other hand, it is possible to reduce the time required for the image conversion processing of the inspection data, and to make the time difference between the two processing extremely small.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram for explaining a pattern inspection method according to an embodiment of the present invention. In the figure, while the object to be inspected 21 ((b) in the figure) is being processed by the scanning processing means 33, an actual image of the area to be inspected 22 is input by a light receiving device of a zoom lens system or the like. The object 21 to be inspected is a mask pattern such as a reticle of a semiconductor device, and tends to have higher density and higher integration.

Next, the image density is detected by the detection means 30, and when the image density is high, the inspection area 22 is reduced to 1 / A by the reduction means 32 (where A is an area ratio). Further, by finely scanning the object to be inspected by the scanning processing means 33 while keeping the control speed of the stage drive system for scanning processing constant, the scanning distance is increased and the scanning processing time is increased. Although there is a means for slightly changing the control speed of the stage drive system, it is necessary to consider the influence of vibration of the drive system.

Then, the image of the object 21 to be inspected in the inspected area 22 which has been reduced is enlarged by the light-receiving device of the zoom lens system, etc.
To enlarge A times. A method of comparing and collating the pattern to be inspected and the pattern for inspection without enlarging is also possible, but the inspection accuracy becomes 1 / A.

Next, the inspection target 35 in the enlarged inspection area 22
The image shown in FIG. 9B is received, processed by the electric processing means 23, and the image data is stored in the storage means 24.

Further, the pattern to be inspected 25 is created based on the image data.

On the other hand, the inspection data 26 corresponding to the inspected object 35 obtained by enlarging the reduced image of the inspected object 22 in the inspected area 22 to A times is extracted, processed by the image conversion processing means 27, and the inspected pattern is obtained. Create 28.

Since the area to be inspected is reduced even if the image density becomes high, the processing load on the image conversion apparatus is reduced and the time for image conversion is reduced.

Next, the image density is detected while synchronizing the time for scanning processing and the time for image conversion processing, and the area to be inspected is determined. Next, the pattern to be inspected 25 ((b) in the figure) and the pattern for inspection 28 ((c) in the figure) are compared and collated to inspect the pattern to be inspected, and a result output 34 is obtained.

The means for detecting the image density, the means for reducing the inspected area according to the image density, the means for enlarging the reduced inspected area, the means for scanning, and the image conversion processing for the inspected area It is also possible to automatically control the amount of time that is performed.

In this way, the difference between the time for scanning the object to be inspected 21 and the time for image processing the inspection data can be made extremely small according to the image density.

〔The invention's effect〕

As described above, according to the present invention, the processing time difference between both patterns can be made extremely small, so that high integration
It becomes possible to process the inspection of the pattern to be inspected, which has a high density, at high speed.

Further, according to the present invention, it is possible to reduce the load of the image conversion processing and to easily align the inspection pattern and the inspection pattern because the influence of the vibration of the drive system is small.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a pattern inspection method according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining a conventional pattern inspection method. (Explanation of reference numerals) 1, 21 ... Inspected object, 2, 22 ... Inspected area, 3, 23 ... Electrical processing means, 4, 24 ... Storage means, 5, 25 ... Inspected pattern, 6 , 26 ... inspection data, 7, 27 ... image conversion processing means, 8, 28 ... inspection pattern, 9, 29 ... comparison and collation means, 10, 34 ... result output, 30 ... image density detection Means, 31 ... Enlargement means, 32 ... Reduction means, 33 ... Scan processing means.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 21/66 J 8406-4M H04N 7/18 B

Claims (1)

[Claims] 1. A scanning processing means (3) for an object (21) to be inspected.
3) scanning processing is performed to obtain an image of the inspection target (21), the image is subjected to signal processing by the electric processing means (23), and the image data subjected to the signal processing is stored in the storage means (24). , A pattern inspection method for comparing and collating an inspected pattern (25) created from stored image data with a reference inspection pattern (28) created from the inspection data (26) by the image conversion processing means (27). At the image density of the object (21) to be inspected, detecting means (30)
When the image density is high, the inspection area (22) is reduced to 1 / A by the reduction means (32) and the inspection data (26) of the inspection object (21) is reduced to perform inspection. The image conversion time from the inspection data (26) to the reference inspection pattern (28) is shortened, and the image of the inspection object (21) in the reduced inspection area (22) is enlarged A times by the enlarging means (31). To increase the inspection accuracy of the inspection object 21 and increase the scanning processing time for acquiring the image of the inspection object (35) enlarged A times, the image conversion time and the scanning processing time. A pattern inspection method characterized by matching.