JPH03139646A - Photomask - Google Patents

Abstract

PURPOSE:To improve the arrangement accuracy of patterns of respective exposure files by shifting length measurement patterns which are exposed in exposure file units in arrangement position in the exposure file units, making the length measurement patterns correspond to the exposure files, and measuring the arrangement accuracy of the patterns of the respective exposure files. CONSTITUTION:The length measurement patterns are exposed in the exposure file units, changed in arrangement position in the exposure file units so as to measure the arrangement accuracy of each file, and made to correspond to the respective exposure files. For example, a mask substrate 1 is exposed to a pattern 2 and a length measurement pattern 6 with a 1st exposure file, to patterns 3 and 4 and a length measurement pattern 7 with a 2nd exposure file, and a pattern 5 and a length measurement pattern 8 with a 3rd exposure file, and the photomask which is completed after the entire exposure has the length measurement patterns 6 - 8 formed in the file units, so that the arrangement accuracy of the exposure patterns can be measured, file by file.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a photomask (or reticle) used in the manufacturing process of semiconductor devices and the like.

We provide a photomask that enables highly accurate monitoring of pattern placement accuracy and improves placement accuracy.

The purpose is to use it for manufacturing semiconductor devices with ultra-fine patterns.

A photomask in which all pattern data is divided and stored in a plurality of exposure files, and a pattern is formed by exposing each exposure file, and has a length measurement pattern exposed for each exposure file.

The arrangement position of the length measurement pattern is changed for each exposure file so that it corresponds to each exposure file,
The configuration is such that it is possible to measure pattern placement accuracy for each exposure file.

[Industrial application field]

The present invention relates to a photomask used in the manufacturing process of semiconductor devices and the like.

In recent years, with the miniaturization of patterns in photomasks for LSI manufacturing, the conditions for pattern misalignment have become stricter.

The present invention can be used for exposing ultra-fine patterns as a photomask that can be monitored to improve placement accuracy.

Here, placement accuracy refers to the position of each pattern on the design data. This refers to the positional accuracy of the pattern actually exposed.

Placement accuracy is included in pattern accuracy, and pattern accuracy consists of dimensional accuracy (accuracy of pattern size) and the above-mentioned placement accuracy.

[Conventional technology]

The entire pattern of a photomask (reticle) for LSI manufacturing is created using multiple exposure files (e.g. magnetic tape, MT
), and are formed by sequentially superimposing the exposed patterns for each exposure file.

FIGS. 4(1) to 4(4) are plan views of patterns exposed for each exposure file and all patterns according to the conventional example.

FIG. 4(1) is a diagram in which a pattern 2 and a length measurement pattern 6 are exposed on a mask substrate l using the first exposure file.

FIG. 4(2) shows patterns 3 and 4 exposed on the mask substrate 1 using the second exposure file. FIG. 4(3) shows patterns 3 and 4 exposed on the mask substrate 1 using the third exposure file. Figure 4 (4) shows the pattern 5 exposed to light.
FIG. 7 is a diagram showing all patterns after exposure using a full exposure file.

In this case, the conventional placement accuracy inspection was performed by measuring the length measurement pattern exposed using only one exposure file (here, the first exposure file).

However, as patterns become finer, the placement accuracy of patterns exposed using files that do not expose length-measured patterns has become a problem.

In general, length measurement patterns can measure not only the placement accuracy (but also the dimensions of the length measurement pattern itself) depending on the measuring device used.

However, the length measurement pattern referred to here is intended to be placed around the reticle, that is, outside the main pattern, to check the placement accuracy.

[Problem to be solved by the invention]

In the conventional example, there is no way to check the placement accuracy of a pattern exposed using a file that does not have a length measurement pattern, and the only way is to estimate it based on the placement accuracy of a pattern exposed using a file that has a length measurement pattern.

An object of the present invention is to provide a photomask with improved placement accuracy by enabling highly accurate monitoring of placement accuracy.

[Means to solve the problem]

The solution to the above problem is a photomask in which all pattern data is divided into multiple exposure files and stored, and a pattern is formed by exposing each exposure file. A photomask that has a pattern, and the placement position of the length measurement pattern is changed for each exposure file so that it corresponds to each exposure file, making it possible to measure the pattern placement accuracy for each exposure file. This is achieved by

[Effect]

The present invention exposes a length measurement pattern for each exposure file,
This makes it possible to measure the placement accuracy of each file.

For this purpose, the arrangement position of the length measurement pattern is changed for each exposure file so that it corresponds to each exposure file.

The reason why the placement accuracy for each file changes is considered to be due to the following factors.

■ Changes over time of the dry plate with photoresist on the mask substrate (due to heat, stress, etc.) ■ Accuracy of the exposure equipment (accuracy of the stage and beam optical system) ■ Flatness of the dry plate surface ■ Charge of the resist on the dry plate, especially, It is thought that the quality of the reproducibility of the exposure device has a large influence. This is because as patterns become finer, variations that were not a problem in the past are no longer ignored.

[Example] Figures 1 (1) to (4) are plan views of patterns exposed for each exposure file and all patterns according to an example of the present invention.

FIG. 1 (1) is a diagram in which a pattern 2 and a length measurement pattern 6 are exposed on a mask substrate 1 using a first exposure file.

FIG. 1(2) is a diagram in which patterns 3 and 4 and length measurement pattern 7 are exposed on mask substrate 1 using the second exposure file.

FIG. 1(3) is a diagram in which a pattern 5 and a length measurement pattern 8 are exposed on a mask substrate l using a third exposure file.

FIG. 1(4) is a diagram showing the entire pattern after exposure using the entire exposure file.

Here, length measurement patterns 6.7°8 for each file are formed around the substrate in 9×9 pieces by sequentially changing their arrangement positions from outside to inside.

In the example, length measurement patterns 6, 7, and 8 for each file are formed on the completed photomask after all exposures are completed, and it is possible to measure the placement accuracy of the exposure pattern for each file. Become.

FIG. 2 is a block diagram illustrating the order in which each file is exposed.

In the figure, ■ to ■ indicate the exposure order. 21.22.23 is the first
-3 exposure files are sequentially called to the exposure device 24 and exposed onto the dry plate 25 one after another. 26°27,
Reference numeral 28 indicates the dry plate after being exposed with the first to third exposure files, respectively.

After all exposures have been completed, the dry plate is sent to the next process.

FIG. 3 is a diagram illustrating an example of measuring placement accuracy using a 9×9 length measurement pattern.

In the figure, the dashed grid indicates absolute coordinates.

A grid of solid lines connects the coordinates of measurement points.

In this case, the measurement point is only the outermost point, and the program in this case displays the positional deviation of all other points as 0.

The measurement was carried out using NIKON's Optical Wave 21 (a measuring device that uses light wave interference).

The measurement results are as follows.

Shrinkage ratio in X direction: 0.13μm Shrinkage ratio in X direction: -0.02μm Because this degree of error occurs for each file.

In the embodiment, by measuring the placement accuracy for each file, it is possible to monitor the placement accuracy with high precision.

〔Effect of the invention〕

As described above, according to the present invention, pattern placement accuracy can be monitored with high precision, a photomask with improved placement accuracy can be obtained, and it can be used for manufacturing semiconductor devices with ultra-fine patterns.

FIG. 3 is a diagram illustrating an example of measuring placement accuracy using a 9×9 length measurement pattern.

FIGS. 4(1) to 4(4) are plan views of patterns exposed for each exposure file and all patterns according to the conventional example.

In fig.

l is the mask substrate 2.3 and 4.5 are patterns.

6.7.8 is length measurement pattern

[Brief explanation of the drawing]

FIGS. 1 (1) to (4) are plan views of patterns exposed for each exposure file and all patterns according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating the order of exposure in each file. 1 // Plan view of conventional A row

Claims (1)

[Claims] A photomask in which all pattern data is divided into a plurality of exposure files and stored, and a pattern is formed by exposing each exposure file, the length measurement being exposed for each exposure file. has a pattern,
The arrangement position of the length measurement pattern is changed for each exposure file so that it corresponds to each exposure file,
A photomask characterized by making it possible to measure pattern placement accuracy for each exposure file.