JPH031522A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To elevate the resolution as compared with the case of one time exposure so as to form a fine resist pattern by using the same photomask and performing plural times of exposure after shifting the positions of the photomask by optional amounts, respectively. CONSTITUTION:Using a photomask 1, the resist 2 on a substrate is exposed at the first time. For the width of the mask pattern 11 of the photomask, the one of 0.1mum is used. Hereby, the part 21, where especially hatting is applied, within the resist 2 is exposed. Next, the photomask 1 is shifted by 0.6mum, and the exposure at the second time is done. Hereby, the part 22, where further hatting is applied, within the resist 2 is exposed. By such two times of exposure, the part 23, where exposure is not applied by the amounts of the width of 0.4mum, occurs. Next, by performing development, a resist pattern 24, where the space 25 has become 0.4mum in width, can be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a resist pattern forming method.

INDUSTRIAL APPLICABILITY The present invention can be widely used in technical fields that use resist patterns, and can be effectively used, for example, as a method for forming resist patterns in the manufacture of electronic components (semiconductor devices, etc.).

[Summary of the invention]

The present invention relates to a resist pattern forming method in which a resist pattern is formed by exposing a resist using a photomask, in which exposure is performed multiple times using the same photomask and shifting the position of each photomask by an arbitrary amount. This makes it possible to form fine resist patterns.

[Conventional technology]

Traditionally, resist pattern forming methods have been used, for example, in lithography technology in the manufacturing process of semiconductor devices, but in recent years, semiconductor devices have been required to be further miniaturized and integrated. In order to increase the accuracy, it is necessary to make the resist pattern even finer. Particularly in semiconductor devices, there is a demand for miniaturization by further reducing the width of lines and spaces.

However, in the current technology, for example, NA=4.5.
When using an exposure machine (stepper), the resolution limit for the width of a line or space was 0.5 μm. This is because the smaller the pattern, the lower the contrast due to the influence of light diffraction.

Symbols in Figure 2! is a light intensity distribution curve when exposed using a mask with a 1.0 μm space. A resist pattern obtained by exposure and development with light having such a distribution curve is ideally formed in a shape corresponding to this intensity distribution curve.

Therefore, if the resist pattern is formed ideally, it is thought that a space with a width of approximately 1.0 .mu.m can be obtained as shown by the curve (2).

On the other hand, what is indicated by the symbol ■ in FIG. 3 is a light intensity distribution curve when exposure is performed using a mask with a 0.3 μm space. The width of the light intensity distribution is narrower than curve ■.1.
It is conceivable that it can be processed finer than a mask with a 0 μm space. However, the width is not necessarily about 0.3 μm, and is at most about 0.5 μm. In addition, the sharper the curve, the better the contrast and the better the shape of the resist pattern. Considering the angle formed by the rise on both sides of ■, that is, the parts indicated by symbols I' and n' in each figure, and the horizontal axis, the angle of curve I is closer to 90'' and sharper than curve ■. .

In this way, the smaller the pattern, the lower the contrast due to light diffraction, resulting in a resolution limit of 0.5μ.
The size was limited to about m, and it was impossible to make it finer than this.

[Problem that the invention seeks to solve]

As described above, with the conventional technology, it is difficult to form a fine resist pattern, for example, a resist pattern with a space width (or line width) of 0.5 μm or less.

Additionally, it would be effective in terms of mask creation and exposure technology if such fine patterns could be formed using a larger mask that maintains contrast, rather than necessarily using a fine mask, but this is considered impossible. , no technological development had been made in this direction.

The present invention solves the above-mentioned problems and provides a resist pattern forming method that makes it possible to obtain a fine resist pattern and, in some cases, to form a resist pattern with finer dimensions than the mask using a larger mask. It is intended to provide law.

[Means for solving problems]

In order to solve the above problems and achieve the above objects, the present invention provides a resist pattern forming method in which a resist pattern is formed by exposing a resist using a photomask. The structure is such that exposure is performed multiple times by shifting the position of the mask by an arbitrary amount.

[For production]

In the present invention, the same photomask is used for multiple exposures, each with a different photomask position, so the resolution can be increased compared to a single exposure, and the resist pattern can be finer than before. can be formed.

Although the effect of the present invention is not necessarily clear, for example, the second
To summarize qualitatively using a diagram, if the first exposure is performed with light of distribution curve I, and the second exposure is performed with light of distribution curve ■' with the exposure position shifted, both I and I' It is thought that the overlapping portions indicated by the symbol "" in FIG. 2 contribute to pattern formation, and that this results in exposure and pattern formation with improved resolution.

For example, using a mask pattern with a space width of 1.0 μm, the light intensity distribution curve ■ when exposed twice with a shift of 0.7 μm is shown in FIG.
m space. Comparing this curve (■) with the curve (2) in Figure 3, it can be seen that the curve (2) is not only narrower, but also has a sharper rise.

It is easy to understand that the difference in width between the curves ■ and ■ and the difference in sharpness (which is an indicator of the magnitude of contrast) bring about extremely effective differences in the formation of a fine cyst-free pattern.

Further, when the present invention is used, a resist pattern of desired dimensions can be obtained using a mask larger than the dimensions of the resist pattern desired to be formed. For example, when a mask with a space width of 1.0 .mu.m was used and exposure was carried out twice at different positions according to the present invention, a resist pattern with a space of 0.4 .mu.m in width was obtained. As described above, the present invention can achieve the surprising effect of being able to obtain a fine resist pattern using a larger mask, which was hitherto unimaginable.

〔Example〕

Specific examples of the present invention will be described below.

However, it goes without saying that the present invention is not limited to the following examples.

FIG. 1A shows one embodiment of the present invention. This is a diagram schematically showing the resist pattern forming method according to this embodiment in the order of its steps. In this embodiment, the present invention is applied to resist pattern formation in the manufacturing process of a semiconductor device.

In this example, the space width of the mask pattern was created wider than the designed value, and after exposure was performed once, the mask pattern was shifted by an arbitrary amount and exposed twice or more.

Generally, it is best to use a positive resist to obtain thin lines, and a negative resist to obtain thin spaces. This embodiment is an example in which the present invention is applied to obtain a narrow space using a negative resist.

In this example, a mask pattern with a spacing of 1.0 μm is used, and the amount of deviation between the first and second exposures is 0.6.
It was carried out as μm. In this case, a space of 0.4 μm was obtained with the resist pattern. In this example, the resist is Image, which is a negative resist.
Reverse resist AZ5214 (manufactured by Hoechst) was used. The exposure device uses a stepper, and NA=
0.45 and an exposure wavelength of 43611 m was used. It is desirable that the resist l- used be one with high resolution, but any resist can be used. Appropriate exposure devices and exposure wavelengths can be used depending on the properties of the resist used.

The present embodiment will be further explained with reference to FIG. 1A as follows.

As shown in FIG. 1A (a), a photomask 1 is used to expose the resist 2 on the substrate 0 for the first time. here,
As described above, the width of the mask pattern 11 of the photomask 1 was 1.0 μm.

In FIG. 1, exposure light is schematically indicated by arrows. As a result, particularly the hatched portion 21 in the resist 2 is exposed.

Next, shift the photomask 1 by 0.6 μm, and
) A second exposure is performed as shown in (). As a result, a further hatched portion 22 in the resist 2 is exposed. The area with double hunting corresponds to the area that was exposed both the first time and the second time.

Due to such two exposures, an unexposed portion 23 having a width of 0.4 μm is created.

Next, development is performed. As a result, as shown in FIG. 1A(c), an unexposed area (portion 23 in FIG. 1A(b))
A resist pattern 24 is obtained in which spaces 25 have a width of 0.4 μm.

The present invention can also be implemented using a positive resist to obtain fine lines in the resist.

Such an example is shown in Figure 1B.

The first exposure shown in FIG. 1B (a) and the second exposure shown in FIG. 1B (b) are carried out in the same manner as in the embodiment shown in FIG. 1A except that a positive resist is used as the resist 2. 1st
In Figure B, the same reference numerals as in Figure 1A indicate the same components.

When development is then performed, unexposed portions of the resist remain in this example, and a fine narrow resist pattern 24' (line) is obtained for the wide space 25'.

〔Effect of the invention〕

As described above, according to the resist pattern forming method of the present invention,
It is possible to form a resist pattern with a fine shape, which has been difficult to form in the past. Further, it is possible to obtain a resist pattern having dimensions finer than the dimensions of the mask pattern.

[Brief explanation of drawings]

FIG. 1A shows an embodiment of the present invention in the order of steps. FIG. 1B shows another embodiment of the present invention in the order of steps. FIGS. 2 to 4 show light intensity distribution curves during exposure. 1... Photomask, 11... Mask pattern, 2
...Resist.

Claims (1)

[Claims] 1. In a resist pattern forming method in which a resist pattern is formed by exposing a resist to light using a photomask, the same photomask is used and the position of each photomask is shifted by an arbitrary amount to form a resist pattern multiple times. A resist pattern formation method that involves exposure.