JPH03259257A - Formation of fine pattern - Google Patents

Abstract

PURPOSE:To make improvement in the contrast of an optical image at the time of exposing of a lower layer by providing phase shifter materials in the wall parts on both sides of the upper layer resist patterns of a PCM (portable conformable mask) resist and exposing a lower layer resist with the upper layer resist patterns and the phase shifter materials as a mask. CONSTITUTION:The phase shifter materials 9 are provided in the wall parts on both sides of the upper layer resist patterns 1 of the PCM (portable conformable mask) resist and the lower layer resist 2 is exposed by irradiation over the entire surface. Namely, the lower layer resist 2 is exposed with the upper layer resist patterns 1 and the upper layer side walls 11 as the mask. The light passing the side wall parts 11 in the upper layer formed of the shifter material is, therefore, inverted in phase by 180 deg. with the light passing the upper layer resist pattern parts 1. The improved contrast of the optical image when the lower layer resist is exposed is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fine pattern forming force method for forming fine patterns in a light exposure process in PCM lithography technology for semiconductor manufacturing.

[Conventional technology]

FIG. 4 is a cross-sectional view showing a conventional fine pattern forming method. In the figure, 1 is an upper layer patterning layer, 2 is a lower layer patterning layer, 3 is a substrate, 4 is a mask for upper layer patterning, and 5 is an upper layer patterning layer. 6 shows the entire surface irradiation light for lower layer exposure, 7 shows the optical image at the time of lower layer exposure, and 8 shows the lower layer pattern after development.

Next, the formation method will be explained.

First, as shown in FIG. 4 (al), a lower resist 2 for flattening and patterning is formed on a substrate 3, and an upper resist 1 is deposited on top of the lower resist 2 to serve as a mask layer for forming fine patterns and exposing the lower layer. The application form is powerful.

Next, as shown in FIG. 4 (bl), a pattern of the upper resist 1 is formed using an exposure mask 4 and upper layer exposure light 5.

Next, as shown in FIG. 4(C), the lower resist 2 is exposed using exposure light 6. Then, as shown in FIG. The upper resist 1 absorbs this exposure light 6 and functions as a mask. The optical image at the time of lower layer exposure is as shown in 7 of Fig. 4+d).

Further, the pattern after developing the lower resist is as shown in 8 in FIG. 4+e).

[Problem to be solved by the invention]

Since the conventional fine pattern forming method is configured as described above, there have been problems such as a decrease in the contrast of an optical image of diffracted light during exposure of the lower layer resist as the upper layer resist pattern density increases.

This invention was made to solve the above-mentioned problems, and an object thereof is to provide a method for forming a fine pattern that can improve the contrast of an optical image during lower layer exposure.

[Means for Solving the Problems] A fine pattern forming method according to the present invention is such that a phase shifter material is provided on both side walls of an upper resist pattern of a PCM two-layer resist, and the lower resist is exposed by irradiating the entire surface. It is something.

Further, the method for forming a fine pattern according to the present invention is based on a PC
An intermediate film that strongly absorbs the lower layer exposure light is formed between the upper resist and the lower resist of the M2 layer resist, and after patterning the upper resist, the intermediate film is etched by wet etching using the upper resist pattern as a mask. At the same time, an undercut is further applied, and both side walls of the upper resist pattern located above the middle abdomen portion removed by the undercut are used as a phase shifter.
The lower resist layer is exposed by irradiating the entire surface.

Further, in the method for forming a fine pattern according to the present invention, depressions are formed in the lower resist at every other section between the upper resist patterns of the PCM two-layer resist, the depressions are used as phase thick, and the lower layer is exposed by full-surface irradiation. The resist is exposed to light.

[Effect]

In this invention, because phase thick is formed on the side wall of the upper resist pattern, or because a recess is provided in the lower resist at every other section of the upper resist pattern to make it phase thick, the lower resist is exposed when the entire surface of the lower resist is exposed. Part of the exposure light will have a phase inversion,
The contrast of the optical image when the lower resist is exposed can be improved.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a method for forming a fine pattern in PCM lithography according to a first embodiment of the present invention. In the figure, 1 is an upper patterning layer, 2 is a lower patterning layer, 3 is a substrate, and 6 is a lower layer. Full-surface irradiation light for exposure, 7
Reference numeral 9 indicates an optical image during exposure of the lower layer, 9 indicates a shifter material, 10 indicates plasma for etchback, 11 indicates waxing of the upper resist layer, and 12 indicates an optical energy image.

Next, the manufacturing method will be explained.

First, as shown in FIG. 1(a), the substrate 3 is flattened and
Then, form a lower resist 2 for patterning, apply an upper resist 1 (which will become a mask layer when forming a fine pattern and exposing the lower layer) thereon, and apply an exposure mask (not shown).
Then, as shown in FIG. 1('b), after patterning the upper resist 1, Si3N4 is deposited on the entire surface of the substrate by the CVD method.
A shifter material 9 such as the above is formed.

Next, as shown in FIG. 1(C), the entire surface is etched back 1.
0 to form sidewalls 11 on the upper resist pattern. Here, by setting the film thickness d of this side wall to λ, the phase of light passing through it is inverted by 180@. Here, n is the refractive index of the shifter material 9, and λ is the wavelength of the lower resist exposure light 6 used in a later step.

Then, as shown in FIG. 1(d), the lower resist 2 is exposed using the upper layer pattern 1 and the upper layer sidewall 11 as a mask. Upper layer side wall portion 11 formed of sister material
The light passing through is 180° with respect to the light passing through the upper pattern part l.
``Since the phase is reversed, the distribution of the optical image 7 and the optical energy image 12 becomes as shown in FIG. 1 (dl), and the contrast is improved.

However, this shifter material 9 exposes the lower layer 2 to deep UV light.

A material such as a SiiNa film is selected that does not absorb this light when the entire surface is exposed using an excimer laser or the like.

Further, a small amount of an absorbing material such as a dye may be added to this chic, and the optical image can be further controlled by changing the amount of this coloring material.

Further, in the above embodiment, the phase shift portion is formed on the side wall of the upper layer pattern, but the side wall of the upper layer itself may be used as a phase shift, and an example thereof will be shown below.

That is, FIG. 2 is a diagram showing a method for forming a fine pattern in PCM lithography according to a second embodiment of the present invention. In the figure, the same reference numerals as in FIG. 14 is an intermediate film formed by wet etching. The manufacturing method will be explained below.

First, as shown in FIG. 2(a), planarization is performed on the substrate 3.
After coating a lower resist 2 such as PMCI resist for patterning, Cr, Mo, Si.

An intermediate film 11 such as a metal such as W that does not transmit light or a metal silicide film is formed by a method such as sputtering, and a PM that becomes a mask layer when forming a fine pattern and exposing the lower layer is formed thereon by a method such as sputtering.
An upper layer resist 1 such as MA or PMCI is coated. Here, the film thickness d of the upper resist 1 is λ. However, n is the refractive index of the PMMA resist or PMGI resist that is the upper resist 1, and λ is the wavelength of the exposure light.

Next, as shown in FIG. 2(b), the upper resist layer 1 is
Patterning is performed using epUV, excimer laser, etc.

Thereafter, as shown in FIG. 2C, the intermediate metal film 13 is removed by wet etching using the patterned upper layer resist 1 as a mask to form an undercut. Then, the upper layer resist 1 of this undercut area is
is used as a 180° phase shifter.

In this embodiment as well, a phase shifter is formed on the side wall of the upper resist 1, as in the above embodiment, so when the entire lower resist 2 is exposed by deep UV, excimer laser, etc. The distribution of the optical image 7 and the optical energy 12 is as shown in FIG. 2(C),
Contrast can be improved.

In the above embodiment, the intermediate film 13 was formed by a method such as sputtering, but this intermediate film 13 was formed by vapor deposition.

A film formed by a method such as coating (provided that it absorbs exposure light) may be used, and the same effects as in the above embodiments can be obtained.

Further, in the above embodiments, the side walls of the upper layer pattern are used as phase shift parts, but the phase shift parts may be provided in the lower layer, an example of which will be shown below.

That is, FIG. 3 is a diagram showing a method for forming a fine pattern on a PCM resist according to a third embodiment of the present invention. In the figure, the same reference numerals as in FIG. 1 indicate the same parts, and I5 indicates a part of the shifter formed. A mask 16 for exposure is a shifter portion formed on the lower resist 2.

Next, the manufacturing method will be explained.

First, as shown in FIG. 3 (al), a lower resist 2 for flattening and patterning is formed on a substrate 3 in the same manner as in the above embodiment, and a fine pattern is formed thereon and a mask is used for lower layer exposure. Upper resist layers 1 are sequentially applied and formed.

Next, as shown in FIG. 3(b), the upper resist 1 is patterned using an exposure mask 4 and upper layer exposure light 5. Then, as shown in FIG.

After that, as shown in FIG. 3(C), 1 of the upper layer pattern
An exposure master 5 is provided for every section, and a depression 16 is formed in the lower layer 2 by an exposure method using the mask 15. Here, the depth d of the depression is assumed to be λ. However, n indicates the refractive index of the shifter, and λ indicates the wavelength of the riffography light.

When the entire surface of the thus formed product is irradiated with light 6 using the upper resist pattern as a mask for lower layer exposure as shown in FIG. 3(d), the recessed portion 6 of the lower resist
A phase shift of 180° occurs at the location where the indentation is not formed, and the phase is reversed from the location where the depression is not formed. Therefore, the optical image at the time of lower layer exposure is as shown in 7 and the optical energy is as shown in 12, and an image with good contrast can be obtained, and patterning accuracy after developing the lower layer resist can be improved.

〔Effect of the invention〕

As described above, according to the present invention, after the formation of the upper resist pattern, the phase shift material is provided on both side walls of the upper resist pattern to serve as a phase shift portion, and the exposure light is provided between the lower resist and the upper resist. After patterning the upper resist layer by etching, the intermediate layer was etched by wet etching, and an undercut was created to utilize both side walls of the upper resist pattern as phase shift parts. Furthermore, after the formation of the upper resist pattern, depressions were formed in the lower resist pattern every other section of the upper resist pattern by an exposure method, and the depressions were used as phase shift parts, so that the optical image was This has the effect of improving the contrast and obtaining a resist image with high rectangularity.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional side view showing a fine pattern forming method according to a first embodiment of the present invention, FIG. 2 is a cross-sectional side view showing a fine pattern forming force method according to a second embodiment of the present invention, and FIG. FIG. 4 is a cross-sectional side view showing a method for forming a fine pattern according to a third embodiment of the present invention, and FIG. 4 is a diagram showing a conventional method for forming a fine pattern. In the figure, l is the upper patterning layer, 2 is the lower butterfly layer, 3 is the substrate, 4 is the mask for upper layer patterning, 5 is the upper layer patterning light, 6 is the entire surface irradiation light for lower layer exposure, 7 is the optical image at the time of lower layer exposure, 8 is the lower layer pattern after development, 9 is the shifter material, 1o is the etchback plasma, 11 is the wadding of the upper layer resist, 12 is the optical energy image, 13 is the intermediate film, 15 is the mask for partially exposing the shifter, 16 is the lower layer This is a shifter section on the resist. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) PCM (Portable Conformable
eMask) In a fine pattern forming method in the light exposure process of lithography technology, a phase thick material is provided on both side walls of an upper resist pattern of a PCM resist, and the lower resist is exposed using the upper resist pattern and the phase shifter material as a mask. A fine pattern forming method characterized by: (2) In a method for forming fine patterns in the light exposure process of PCM lithography technology, an intermediate film having strong absorption for the lower layer exposure light is formed between the upper layer resist and the lower layer resist of the PCM resist, and After patterning, the intermediate film is etched by wet etching using the upper resist pattern as a mask, and an undercut is further made on the intermediate film, so that the upper resist pattern located above the middle portion removed by the undercut is etched. A fine pattern forming method characterized in that the lower resist layer is exposed by full-surface irradiation using both side wall portions as a phase thick. (3) In a method for forming fine patterns in the light exposure process of PCM lithography technology, depressions are formed in the lower resist at every other section between the upper resist patterns of the PCM resist, and the depressions in the lower resist are used as phase thicks. , a fine pattern forming method characterized by exposing a lower resist layer by full-surface irradiation.