JPH0132045Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a reticle used to form a fine pattern on a photomask blank or the like by a reduction projection exposure method.

[Conventional technology]

When forming a desired pattern using a conventional 10:1 or 5:1 reduction projection exposure device, a reticle having a pattern that is 10 times or 5 times larger than the desired pattern is set on a support stand. Let's do it. For example, in order to obtain a photomask 2A in which a pattern 22 of a light-shielding film made of metal such as chromium as shown in the figure is formed on a transparent glass substrate 21 as shown in FIG. 8b, as shown in FIG. Use a reticle 1A like this. In the same figure,
11 is a light-transmitting glass substrate, and 12 is a pattern of a light-shielding film made of chromium.

First, a positive photoresist is applied onto a photomask blank in which a light-shielding film such as chromium is coated on the entire main surface of the glass substrate 21, and this resist is exposed to light through the reticle 1A and developed. By etching the light shielding film using the remaining resist as a mask and removing the unnecessary resist, a photomask 2A as shown in FIG. 2B is obtained. At this time, reticle 1A
When setting the image to the reduction projection exposure device,
Alignment is performed by matching a pair of +-shaped and --shaped alignment marks as shown by 4 to marks on the reticle support base as shown by broken lines. Similarly, in order to obtain a photomask 2B having a pattern as shown in FIG. 9b, a reticle 1B as shown in FIG. 9a is used. In addition, the marks are a combination of + and -,
This is to make it easier to distinguish between the front and back of the reticle and the rotation.

[Problem that the invention attempts to solve]

In the conventional method described above, even when forming patterns that have substantially the same shape but differ only in their angles, as shown in FIGS. 8b and 9b, for example, Each requires a different reticle. Furthermore, when attempting to form a pattern with lines oblique to the X and Y directions as shown in Figure 9a by direct writing with an electron beam, the electron beam only moves in the X and Y directions. Because this is not done, the diagonal lines are expressed in steps when viewed microscopically, resulting in uneven pattern edges and adversely affecting the pattern accuracy of the photomask.

[Means for solving problems]

The reticle of the present invention places alignment marks corresponding to each of a set of marks on the reticle support base at an angle θ (θ≠
0°).

[Effect]

If the marks rotated by θ are aligned with one set of alignment marks and set in a reduction projection exposure apparatus, the pattern rotated by θ is transferred.

〔Example〕

FIG. 1a is a plan view of a reticle showing an embodiment of the present invention. The reticle 1a of this embodiment is
For a pattern 12 (in the illustrated example, it is F-shaped, but this shape is arbitrary) made of a light-shielding film (the material of which is arbitrary), four concentric circles are formed at 45° intervals.
Pairs of alignment marks 13a, 14a, 13b,
14b, 13c, 14c and 13d, 14d are arranged.

Each pair of alignment marks are shown in Figure b.
As shown in , it corresponds to a pair of marks 31 and 32 provided on the reticle support stand 3a of the reduction projection exposure apparatus, and the cross-shaped white part of mark 31 has +
Positioning is performed so that the shaped alignment marks 13a to 13d are inserted, and the - shaped alignment marks 14a to 14d opposing the band-shaped white portion of the mark 32 are inserted. 33 is a through hole for vacuum suction;
The reticle 1a is placed on the reticle support stand 3a, and after alignment as described above using an optical microscope or the like, it is fixed by vacuum suction.

FIG. 2 is a perspective view schematically showing the structure of the reduction projection exposure apparatus. As mentioned above, reticle 1a
while fixing the XY on the reticle support base 3a.
A transfer substrate 5 made of a photomask blank coated with photoresist is fixed on a moving table 4, and exposed by irradiating it with light from a light source 6. 7
8 is a condenser lens, 8 is a light shielding plate for controlling the exposure area, and 9 is a reduction projection optical system.

As mentioned above, exposure is carried out using the reticle 1a fixed on the reticle support 3a. At this time, as shown in FIG.
Alignment mark 1 for marks 31 and 32 on a
By combining 3b and 14b, an erect pattern like the photomask 2a shown in FIG. 3b can be obtained. On the other hand, as shown in Figure 4a, mark 3
Positioning marks 13a, 14 for 1, 32
If you match a, you will get the photomask 2b shown in b of the same figure.
A pattern rotated 45 degrees clockwise is obtained as shown in the figure. Similarly, by using a pair of alignment marks 13c, 14c or 13d, 14d,
Patterns rotated counterclockwise by 45 degrees and 90 degrees, respectively, with respect to the pattern in FIG.
Patterns such as those shown in Figures a-d can be formed by the same reticle.

As mentioned earlier, in order to easily distinguish between the front and back of the reticle and the rotation, we use alignment marks with different shapes, + and -, as shown in Figure 1. Only the above four patterns can be formed by combining the reticle 1a and the reticle support 3a, but it is possible to form only the above four patterns. However, you can use a reticle in which the positions of the pair of +-shaped and --shaped alignment marks are swapped, or use a reticle on the reticle support 3a. If you switch the positions of the +-shaped mark and the strip-shaped mark, you will get Figure 6a.
Patterns as shown in ~d can be formed.

Furthermore, it is not always necessary to distinguish between front and back and rotation using the alignment marks, and in that sense, the pair of alignment marks do not necessarily have to have different shapes. In particular, if the arrangement is asymmetrical, as shown in FIG. 7a, for example, it is possible to determine whether the reticle is front or back and whether the reticle is rotated, even if the alignment marks are of the same shape. The reticle 1b of this embodiment has six identical +-shaped alignment marks 15a to 15f arranged at 45° intervals.
As shown in Figure b, two +-shaped marks 34, 3
5 with reticle supports 3b arranged at 90 DEG intervals, it is possible to form a pattern similar to that shown in FIGS. 5a-d. In addition, in this embodiment, it goes without saying that the alignment marks rotated by 90 degrees to each other form a pair.
Two pairs of alignment marks used to form two patterns rotated by 90 degrees with respect to each other have one mark in common. For example, Figure 5a
The alignment marks 15b and 15d are used to form the pattern shown in d, and the alignment marks 15d and 15d are used to form the pattern shown in d of the same figure.
5f is used, and the alignment mark 15d is a common component of each pair.

Above, we have explained an example of forming a pattern rotated by 45 degrees using a pair of +-shaped or --shaped alignment marks, but the shape of each alignment mark can be arbitrary, and the arrangement can also be It is not limited to ゜ intervals, nor is it limited to equal intervals. Further, for example, three alignment marks may be used for one alignment (of course, three marks are also provided on the reticle support base corresponding to each mark), and a plurality of sets may be arranged.

Further, in the above-described embodiments, a case was explained in which a photomask was formed using a positive photoresist, but the present invention does not limit the types of resists, the types of objects to be transferred, or their uses. Not even.

Although it is possible to obtain the same effect as the present invention by arranging multiple sets of marks on the reticle support, it is desirable that the reticle support is highly versatile. In this sense, it is preferable to arrange a plurality of sets of alignment marks on the reticle side as in the present invention.

[Effect of idea]

As explained above, according to the present invention, by arranging a plurality of sets of alignment marks corresponding to the marks on the reticle support base, a plurality of patterns having the same shape but differing only in angle can be formed by the same reticle. Furthermore, when forming a reticle pattern, by selecting an angle that increases the number of lines parallel to the XY direction, it is possible to reduce diagonal lines and reduce unevenness at the edges of the pattern, thereby increasing precision.

[Brief explanation of the drawing]

1 to 5 are views showing an embodiment of the present invention, in which FIG. 1a is a plan view of a reticle, FIG. 1b is a plan view of a reticle support, and FIG. 2 is a configuration of a reduction projection exposure apparatus. 3 and 4 are plan views showing the relationship between the alignment angle of the reticle and the pattern to be formed, FIG. 5 is a plan view showing patterns that can be formed, and FIG. FIG. 7 is a plan view showing a reticle and a reticle support base showing another embodiment of the present invention, and FIGS. 8 and 9 are plan views showing a conventional example. . 1a, 1b... Reticle, 3a, 3b... Reticle support base, 5... Transferred substrate, 11... Glass substrate, 12... Light shielding film, 13a to 13d,
14a to 14d, 15a to 15f... alignment marks, 31, 32, 34, 35... marks.

Claims (1)

[Scope of utility model registration request] In a reticle that has a predetermined pattern and is used to transfer the pattern onto an object by a reduction projection exposure method, for positioning each mark corresponding to a set of marks provided on a reticle support base of a reduction projection exposure device. A reticle characterized in that a plurality of sets of marks are arranged around the pattern and mutually rotated by an angle θ (θ≠0°).