JPH0845810A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To provide a formation of a resist pattern whereby it is possible to produce a single line of resist pattern as a pattern of high precision close to a desired pattern size and to enlarge a range of a focal depth. CONSTITUTION:A resist is exposed to light by first exposure using a first mask 11 having a desired pattern 12a and a dummy pattern 12b other than the desired pattern 12a. Then, the resist is exposed to light by second exposure using a second mask 21 for eliminating the dummy pattern 12b. The resist is then developed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist pattern forming method suitable for use in a manufacturing process of semiconductor devices and the like.

[0002]

2. Description of the Related Art At present, in the manufacture of semiconductor devices, a lithography technique for forming a pattern using light is used. A resist pattern is formed in the first half of the lithography process. Most of the formation of this resist pattern is performed by a combination of a reduction exposure device (stepper) and a novolak + naphthoquinonediazide element positive resist.

In the stepper, the reticle is reduced to an exposure field of 20 mm × 20 mm through a lens, and at the same time, the wafer stage is sequentially moved to expose the entire surface of the wafer.

In recent years, as the degree of integration of semiconductor devices has increased, the processing size has become finer, and the slight aberration of the stepper lens has a great influence on the dimensional accuracy of the resist pattern. The aberration of the stepper lens becomes more remarkable as it approaches the outer circumference of the exposure field of the stepper.

[0005]

On the other hand, in forming a resist pattern, the depth of focus (DOF: Depth Of F
ocus) is the most important point, but it is becoming difficult to secure a large size as the processing size becomes smaller. In particular, it is more difficult to secure the DOF of a single resist pattern (Isolate line) than the repeated resist pattern (line & space). In the present specification, a single resist pattern refers to a pattern having a space twice or more that of a line, and hereinafter referred to as a single pattern. In addition, the repeated resist pattern is a pattern in which the space is 1 time or more and less than 2 times the line, and is referred to as a repeated pattern hereinafter.

Further, the influence of the aberration of this lens is more likely to be received in the single pattern than in the repeated pattern, so that the single line on the outer periphery of the exposure field is the most inaccurate.

FIG. 4 is a diagram showing a mask for forming a single line pattern for explaining the conventional method. In particular, a mask (reticle for forming a single line at a corner (corner) and a center in an exposure field). 1), the shape of the mask 1 for forming a substantially square single line pattern is that a chromium thin film pattern 2 is formed in a vertically long shape on a quartz plate 1a. Since the mask 1 forms a single pattern at the corner and the center in the exposure field, the chrome thin film pattern 2 also has the center A, the corners B, C and D.
And E.

When this mask 1 is used to perform one ordinary exposure and development, the depth of focus curve is as shown in FIG. 5, and the curve corresponding to the chromium A in the central portion is close to the desired pattern size. The pattern of the corners (B to E) is good, but a fine curve is formed in the vicinity of the lower limit of the pattern specification, and the range of the depth of focus (range) as a whole.
Was narrow and the resolution was not good.

On the other hand, FIG. 6 shows a mask 11 for forming a repetitive pattern at a corner portion and a central portion in an exposure field. A chromium thin film pattern 12 is formed at the corner and center of the mask 11. When this mask 11 is used to perform one exposure and development, the depth of focus curves of the patterns F, G, H, I, and J at the center of each part are close to the desired pattern dimensions as shown in FIG. Was small and highly accurate.

The repeated pattern is Fo due to the influence of diffracted light.
It is highly tolerant of changes in cus and is also less susceptible to lens aberrations. That is, the depth-of-focus curve is convex upward and is tight in the individual patterns A to E, whereas the central patterns F to J of the repeated patterns are convex downward and the curve is gentle.

Therefore, the present invention is to provide a resist pattern forming method capable of obtaining a resist pattern of a single pattern as a highly accurate pattern close to a desired pattern size and further expanding the range of depth of focus. To aim.

[0012]

In order to solve the above-mentioned problems, according to claim 1 of the present invention, a resist is formed using a first mask in which a desired pattern and a dummy pattern other than the desired pattern are arranged. 1 exposure, and then a second resist is applied using a second mask to eliminate the dummy pattern.
It is characterized in that the resist is exposed and then developed.

According to a second aspect of the present invention, the desired pattern in the first aspect is a single pattern.

Further, according to a third aspect of the present invention, the arrangement of the desired pattern and the dummy pattern in the first aspect is a repeating pattern.

[0015]

According to the present invention, the dummy pattern 12b is erased after exposing the resist with the mask 11 having the desired chrome thin film pattern 12a and the dummy pattern 12b which form the repetitive pattern as shown in FIG. The same resist portion is exposed with the dummy pattern 22. Therefore, the good exposure accuracy of the repeated pattern can be utilized in the single pattern.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining an embodiment of the present invention, which is a case where a resist pattern of a single line is formed at a corner portion and a central portion in an exposure field at the time of manufacturing a semiconductor device.

In the present embodiment, first, a mask 11 (FIG. 1) in which the same chromium thin film pattern as the mask shown in FIG. 5 is repeatedly applied at each site is used to perform resist exposure by a reduction exposure apparatus (not shown). Was exposed (first exposure).
Of the repeated pattern of the mask 11, the central portion 12a is a chromium thin film pattern for obtaining a desired resist pattern, and the patterns 12b on both sides thereof are dummy patterns. At the four corners and the central portion in the exposure field, the resist exposure is performed with three patterns corresponding to the mask 11, respectively. Part 3 in Figure 2 (a)
An individual resist exposure pattern is shown. In the figure, 10 is a resist, 15 is an exposed portion, and 16 is an unexposed portion. Next, FIG.
The mask (second exposure mask) 21 shown in (b) is used to expose the same exposure field as the above-described exposure field (second exposure).

A chrome thin film pattern 22 is formed as a dummy pattern on the mask 21 shown in FIG. 1 (b). This chrome thin film pattern 22 is shown by a broken line in FIG. It is formed at a position that covers the central chrome thin film pattern 12a among the three chrome thin film patterns arranged at the corners and the center of the exposure mask and does not overlap the left and right chrome thin film patterns 12b. Therefore, in the second exposure using this mask 21, the resist exposure pattern formed by the chromium thin film patterns 12b on the left and right of each part of the mask 11 shown in FIG. 1A is shown in FIG. 2B. And the pattern at the center is substantially exposed.
As a result, the single pattern remains as 6, and becomes a pattern for forming a resist pattern.

After such second exposure, ordinary development was carried out to obtain resist patterns each having a single pattern.
As shown in FIG. 3, the obtained single pattern has the same curve as the depth of focus curve shown in FIG. 7, and the single pattern has good resist pattern characteristics as in the above description. .

[0020]

As described above, according to the present invention, after the exposure is once performed using the mask in which a plurality of patterns having a good exposure accuracy such as a repetitive pattern is arranged, the unnecessary pattern is erased to obtain a desired single pattern. The exposure is performed to obtain Therefore, according to the present invention, a single pattern (desired pattern) can be obtained with high accuracy, and
The range of depth of focus can be expanded.

Furthermore, one of the methods of improving the resolving power of the stepper, that is, the method of injecting light from an oblique direction (oblique incidence illumination, etc.) is effective only for the repeating pattern, but the repeating pattern according to the present invention is used. It is also possible to apply it to a single line.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an example of the present invention.

FIG. 2 is a partially enlarged view showing resist exposure according to an example of the present invention.

FIG. 3 is a depth of focus curve obtained according to an embodiment of the present invention.

FIG. 4 is a mask for forming a single line for explaining a conventional method.

5 is a focal depth curve when a resist pattern is formed using the conventional mask of FIG.

FIG. 6 is a conventional repetitive pattern forming mask.

7 is a depth of focus curve when a resist pattern is formed using the mask of FIG.

[Explanation of symbols]

 1,11,21 Mask (reticle) 2,12,22 Chrome thin film pattern 10 Resist 11a, 12a, 22a Quartz plate 15 Exposed part 16 Unexposed part 16a Unexposed part Vanished part

Claims (3)

[Claims] 1. A resist is first exposed using a first mask having a desired pattern and a dummy pattern other than the desired pattern, and then a second mask for eliminating the dummy pattern is used. A second exposure of the resist, and then developing the resist. 2. The method for forming a resist pattern according to claim 1, wherein the desired pattern is a single pattern. 3. The resist pattern forming method according to claim 1, wherein the desired pattern and the dummy pattern are arranged repeatedly.