JPS5846054B2 - photo mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photomask used in photolithography and the like.

For example, in the manufacturing process of semiconductor devices, a selective etching process using photolithography has become an important element.

A photomask is used for selectively exposing the photosensitive resin layer to photoetching, and this photomask is made by vapor-depositing a metal such as chromium (Cr) on the surface of a translucent plate-like member, and forming the photomask according to the mask pattern. Selectively etched.

Incidentally, in recent years, semiconductor devices, including integrated circuits (ICs), have tended to become more miniaturized, and along with this, there has been a demand for finer processing of photomask patterns.

However, since the fine patterns of photomasks are formed by a selective etching method using photolithographic technology, the dimensional accuracy of the pattern depends on the characteristics and shape of the mask (photoresist) or the concentration of the etching solution. There is considerable variation between them.

Therefore, conventionally, after the photomask has been manufactured, the pattern dimensions of each photomask have been measured using special equipment, but this involves extremely complicated work and is subject to individual errors by the measurer.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a photomask that can be used to measure the dimensions of an individual with a small amount of measurement error through simple operations.

In order to achieve such an object, the present invention has two regions, and a pattern in which each region is adjacent or connected is provided in a region other than the main pattern forming region.

Hereinafter, the present invention will be explained in detail using Examples.

FIG. 1 is an external configuration diagram showing an embodiment of a photomask according to the present invention.

In the figure, there is a rectangular translucent plate-like member 1, one surface of which is large enough to correspond to the size of a semiconductor wafer, for example, a main pattern formed by selective etching of a chromium-deposited film. 2 is formed.

A measurement pattern 3 is formed simultaneously with the main pattern 2 in an area other than the formation area of the main pattern 2, and this measurement pattern 3 has one of the embodiments shown in FIGS. 2a to 2C. It has two patterns.

That is, FIG. 2a consists of two rectangular regions 4 and 5, which are in point contact at each corner, and FIG. and 5, each of which is slightly smaller in size and separated from that in Figure 2a, and in Figure 2C, each area is slightly smaller in size than that in Figure 2a. It is slightly larger than the case, and has a shape that looks like it is overlapped at each corner.

In other words, if the measurement pattern 3 having such a configuration is formed at the same time as the formation of the main pattern 2, excess or insufficient selective etching performed during the formation of the main pattern 2 will be directly reflected in the measurement pattern 3. become.

If the pattern shown in FIG. 2A is normally etched, the pattern shown in FIG. 2C is over-etched, and the pattern shown in FIG. 2C is under-etched.

Moreover, each of these patterns can be clearly distinguished by observation using a microscope, etc., and discrimination errors due to individual differences among observers are completely eliminated.

In this example, one set of measurement patterns 3 is provided in an area other than the main pattern 2 formation area, but two sets of measurement patterns are provided, thereby forming the main pattern 2 within the tolerance range. It is also possible to clearly determine whether the

That is, as shown in Fig. 3, for example, one side is 5 μm.
Areas 6 and 7 each consisting of a rectangle - 0.2 μ at the corner
A measuring pattern 8 having a shape that is superimposed on m squares, and areas 9 and 10 that are also rectangular with a side of 5 μm.
Measurement pattern 1 with a distance of 0.2 μm at each corner.
1 and 2 are formed simultaneously with the main pattern 2.

In this way, the limit of dimensions that can be selectively etched without separating the regions 6 and 7 of the measurement pattern 8 is 4.
．． Each area 9, 1 of the measurement pattern 11 is 8 μm square.
The limit of the dimension that can be selectively etched to avoid formation of overlapping 0's is 5.2 μm square.

Therefore, when the two sets of measurement patterns 8 and 11 shown in FIG. If you can recognize that
It can be directly read that the dimensional accuracy of 5±0.2 μm is satisfied.

Further, it has been found that, for example, when forming a window such as a contact hole in an insulating film formed on the upper surface of a semiconductor substrate, the etching rate varies depending on the area of the contact hole due to various parameters during selective etching.

In this case, there are times when it is desired to recognize which of the contact holes having different areas are over-etched or under-etched.

In such a case, as shown in FIG. 4, various measurement patterns formed from areas corresponding to the area of each contact hole in the main pattern are provided, and if judged as shown in the example, which contact hole It is possible to easily identify whether etching has been over-etched or under-etched.

In addition, when trying to achieve such a purpose, each measurement pattern corresponding to one contact hole may be
By configuring two sets as shown in the figure, it is possible to easily identify whether or not each contact hole is within the tolerance range.

Further, in each of the above-mentioned embodiments, each region of the measurement pattern is formed of, for example, a chromium vapor-deposited film formed on the surface of a light-transmitting plate-like member, but it is not necessarily limited to this. The areas of the measurement pattern may be the areas of the chromium vapor-deposited film on the pack.

For example, the patterns of each aspect described in this example are shown in FIG.
As shown by C to C, two rectangular regions 4 and 5 are formed in outline on the chromium-deposited film 12 so as to be in contact with, connected to, or separated from each other at the corners.

Furthermore, in each of the above-mentioned embodiments, the two regions constituting the measurement pattern are rectangular, but it goes without saying that the same effect can be obtained even if the two regions are round or circular. .

That is, when it is made into a round shape, as shown in Fig. 6, the sixth
Fig. 6A shows a state in which etching has been performed normally, Fig. 6 shows a state in which overetching has been performed, and Fig. 6C shows a state in which etching is insufficient.

As described above, according to the photomask according to the present invention,
It becomes possible to determine whether a mask pattern formed by selective etching is normally formed with a simple operation and without individual measurement errors.

[Brief explanation of the drawing]

Fig. 1 is an external configuration diagram showing an embodiment of a photomask according to the present invention, Fig. 2 is a plan view showing a measurement pattern which is the main part of the present invention, and Figs. FIG. 3 is an explanatory diagram showing another example of such a photomask. 1... Translucent plate member, 2... Main pattern, 3°8.11... Measurement pattern, 4,
5,6,7゜9.10... Area, 12...
・Chromium vapor deposition film.

Claims (1)

[Claims] 1. A photomask characterized in that a pattern having 12 regions, each of which is close to each other or connected to each other, is provided in a region other than the main pattern forming region at the same time as the main pattern.