JPS61179535A - Layered structure resist and pattern forming method applying it - Google Patents

Abstract

PURPOSE:To exclude the effects caused by the removing liquid in the process of melting and removing of the contrast enhanced layer and the resist and omit the complicated removing process, by forming the laminated structure of the photosensitive resin and the soluble organic film which is layered on the photosensitive resin, contains the diazo compound with bleaching or discoloring property caused by radiation and is removed by the developer of photosensitive resin. CONSTITUTION:The laminated structure is formed with the photosensitive resin and the soluble organic film which is laminated on the photosensitive resin for pattern forming, and added bleaching or discoloring property caused by radiation. In the deionized water of 100cc, for example, 10g weight of pullulan being polysaccharide and about 0.2g weight of diazo compound with bleaching for the wave length region from 436nm to 365nm are dissolved. This aqueous solution is in gelled state or insoluble so that it contains no precipitate and is very clean. On the ordinary resist of 1.5mum thickness, this aqueous solution is spread to form a 0.5mum thick film and the two-layered structure is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention adds a bleaching action to radiation, such as ultraviolet rays, and increases the transmittance after complete bleaching [horizontal axis: exposure energy (3), vertical axis: transmittance] The characteristic equation (7), Y=
When AX + B, A tends to be large and B tends to be small.
The present invention relates to fine pattern formation that improves the resolution achieved by conventional exposure methods.

BACKGROUND OF THE INVENTION The high degree of integration and density of integrated circuits has increased due to advances in conventional lithography technology. The minimum line width has become around 1 μm, and in order to achieve this processed line width, there are two methods: ultraviolet exposure using a reduction projection method with a high aperture lens (high NA), and an electron beam that draws a straight line on the substrate. Examples include exposure method and proximity exposure method using X-rays. However, in order to form a pattern without sacrificing throughput, the former method of ultraviolet exposure using a reduction projection method is best. However, the resolution R of ultraviolet exposure is expressed by the following Rayles law.

R-○, 6×λc, Ax (1+1/m)...
...... (1) λ; wavelength N, A; lens aperture m; magnification In order to improve the resolution, shorter wavelength, higher N, and A can be considered, but the performance of currently available optical systems is, for example , the wavelength is 3
When 66 nm (i-line) and N and A are 0.4, the resolution R is 0.6 μm, which is said to be inferior to the resolution of electron beam exposure and X-ray exposure.

However, in 1983, GE's B, F, Gr.
If fing et al. announced a method to improve the resolution and pattern shape by laminating a contrast-enhanced layer that promotes the contrast of the light intensity profile on the resist for pattern formation (Cont.
last Enhancecl Photolitho
Giaphy.

B,F,Griffing at al,Eng.
E-ED, VOL.

EDL-4, A1, Jan, 1983). According to them, the normal reduced projection method (λ; 436 nm,
It is reported that resolution of up to 0.4 μm is possible with N, A; 0.32).

As a result of research by the inventors, it has been found that the characteristics of a patterned organic film to enhance contrast must be as follows.

Referring to FIG. 3, first, problems in light exposure, such as the reduction projection method in general, will be described.

The output light intensity profile in the reduction projection exposure method is
Processing is performed using the optical lens system. To explain, when exposure 4 is performed through the reticle 5 [Fig. 3A], the ideal input light intensity profile without diffraction can be said to be a perfect rectangular wave.
The contrast C is expressed by the following formula. At that time, contrast C becomes 100% [
Figure 3B]. The input waveform passes through an optical lens and is determined by the transfer function of the optical lens system [Figure 3C]
, after being Fourier transformed, the output waveform becomes close to the shape of a cosine wave, and the contrast C also deteriorates. This deterioration of contrast greatly affects pattern shape, such as resolution and pattern shape. Incidentally, if the resist pattern resolution becomes 2' or 1', pattern formation becomes impossible.

Therefore, in the characteristic curve shown in Figure 4, in the region where the exposure time (exposure energy) is small, the transmittance to ultraviolet rays is small (the increase in 111!1io is small), and in the region where the exposure energy is large, the transmittance to ultraviolet rays is small. big(
I! Na! By using a resist film with a tendency of increasing the contrast C value and passing the output waveform shown in the third diagram above through this film, it was discovered that the contrast C value tends to increase.

In order to explain this more quantitatively, we will discuss IBM's F,
A report by H., Dtll et al. (Characterizati
on of Po5itivePhctcrist
, F.H., Dill et al., IEEE-E
D, VOL, ED-22, A7. Tuly, 1
975), the parameters given in the exposure absorption term A of the positive resist are used. Generally, A is indicated, and it is desirable that the A value tends to be small for contrast enhancement. To make A have a dog-like tendency, d (film thickness) should be made thin and T (
0) (initial transmittance), T(→(final transmittance)) must be in the same ratio.

By the way, in the above-mentioned announcement by GE, the material of the contrast enhanced layer has not yet been disclosed. Second
A conventional pattern forming process using contrast enhanced lithography (abbreviated as CEL) by GE's Griffin et al. will be described with reference to the drawings. Board 1
Resist 2 is applied by rotation on top (Fig. 2a). Next, apply a contrast enhanced layer (CEL) on resist 2.
) Apply 3 times (Fig. 2b). Then, it is selectively exposed to ultraviolet light 4 using a reduction projection method (FIG. 2C). At this time, a part of the resist 2 is also selectively exposed. And C.E.
Remove the entire L3 [Figure 2d]. Finally, a normal development process is performed to form a resist 2 pattern.
Figure 2 E]. In the method described above, the conditions that CEL must have are that it has the property of enhancing contrast, that it prevents dissolution with the underlying pattern forming resist 2, and that the removal liquid used to remove CEL 3 has the characteristics of resist 2. One of the advantages is that it does not deteriorate the opening. This condition that must be met imposes significant restrictions on the material composition. Furthermore, from a process point of view, the CEL removal step is complicated and dangerous.

Problems to be Solved by the Invention The present invention takes into account matching with the underlying pattern forming resist (photosensitive resin) and eliminates the influence of the removal liquid when dissolving and removing the contrast enhanced layer and the resist. , the purpose is to omit the complicated removal process.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has a bleaching or fading effect on a conventional photosensitive resin by radiation, such as ultraviolet rays, so that the number of transmitted lines after complete bleaching is For example, s
0% or less, and uses a layered structure in which a pattern-forming organic film is formed which has a water-soluble property that is easily soluble in a developer such as an alkaline aqueous solution in the development process of a pattern-forming resist (photosensitive resin). .

Function The organic film for pattern formation used in the present invention must have water-soluble properties that are easily soluble in the developer or rinse solution of the underlying photosensitive resin. For example, it can be said that the ultraviolet transmittance of a commonly used novolac-based quinonediazide positive resist is limited by the weight percent of naphthoquinonediazide sulfonyl chloride, which is a sensitizer, relative to the novolac resin. The present inventors found that since the pattern-forming organic film itself does not need to remain as a pattern, it is possible to increase the weight percentage of naphthoquinonediazide sulfonyl chloride, and as a result, the dissolution rate also increases in an alkaline aqueous solution. I discovered something.

Yet another method is to use a water-soluble polymer as a pace polymer and to add a compound having a bleaching or bleaching effect to ultraviolet rays, such as a bleaching dye, to create an organic film for contrast enhancement and water-soluble polymerization. Properties can be added.

As the first invention, a resist (
A layered resist with a laminated structure consisting of a photosensitive resin) and an organic film on the upper layer that is water-soluble and has a bleaching or fading effect against radiation.

A second invention provides a layered resist having a laminated structure consisting of a resist as a lower layer, a water-soluble organic film as an intermediate layer, and a pattern-forming organic film as an upper layer that is water-soluble and has a bleaching or fading action against radiation.

Furthermore, as a third invention, the layered structure resist of the first invention is selectively exposed, and the two-layer structure of the water-soluble organic film on the selectively exposed resist is simultaneously developed, and after development, the fading property is reduced. Alternatively, a pattern forming method characterized in that a water-soluble organic film containing a bleaching compound is removed, and as a fourth invention, selectively exposing using the layered resist of the second invention, A pattern forming method characterized in that the selectively exposed three-layer structure of the resist, the water-soluble organic film, and the pattern-forming organic film is simultaneously developed, and after development, the pattern-forming organic film and the water-soluble organic film are removed. provide.

The key point of the inventions in Bookcases 3 and 4 is that there is no step of removing the so-called contrast-enhancing layer in advance, but that it is simultaneously removed by the developer of the underlying patterning resist.

The feature of the present invention is that it is water soluble and does not bleach or fade. 'stomach.

Example (Part 1) Examples of water-soluble polymers used as a pace polymer include polysaccharides, proteins, polyvinylpyrrolidone, and bonivinyl alcohol. Use 10 g of deionized water (made by the Institute) dissolved in 100 g of deionized water (!e.
Approximately 0.2 g of a diazo compound having a bleaching effect in the wavelength range from 36 nm to 366 nm was dissolved. The aqueous solution at this time was gel-like or insoluble, with no precipitates and was very clean. This aqueous solution was made into a two-layer structure in which a normal resist was coated to a thickness of 1.6 μm and then a layer of 0.5 μm was coated.

Note that the A value of the organic film used as a coating film was as high as 6. This value could be increased to 10 or more by adding a diazo compound.

Next, a pattern forming method using the pattern-forming organic film prepared above will be explained with reference to FIG.

A resist 2 with a thickness of 1.0 to 2.0 μm is placed on a substrate 1 such as a semiconductor.
Coat and form thickly [Fig. 1A]. Next, the pattern-forming organic film 6, which is water-soluble and has a bleaching or fading action against radiation, is laminated on the resist 2 (FIG. 1B). At this time, no dissolution between the lower layer resist 2 and the upper layer pattern forming organic film 6 was observed. Next, selective exposure is performed using ultraviolet rays using a reduction projection exposure method 4 (FIG. 1C). At this time, as explained in Fig. 3, the incident light undergoes Fourier transformation and the contrast value C deteriorates. After passing through the space mask, the contrast C value is so%, and there is no normal resolution. However, when the A parameter of the pattern-forming organic film 6 is set to 6, the incident light with a contrast of 50% passing through the pattern-forming organic film 5 has a contrast of 7.
As a result, it was enhanced to zero and entered the resist layer 2 below. Thereafter, when developing the resist 2 with a developer such as an alkaline developer, the pattern formation process is performed using the Inga f111-11. By continuing to carry out the step 1 = p exposure, a part of the resist 2 exposed to the normal contrast-enhanced incident light is developed and removed [FIG. 1D].

As a result, it was possible to clearly resolve lines and spaces of 0.5 μm.

Note that the present invention does not limit the scope of the present invention to arbitrarily select the exposure wavelength by matching the bleaching action or fading action of the organic film.

As described above, the pattern-forming organic film used in the present invention has a water-soluble function, which greatly facilitates the process, improves throughput, and enables stable pattern formation even with changes in exposure time or development time. I found out that it can be done.

(Part 2) Synthesize the base polymer with novolak resin, orthonaphthoquinonediazide sulfonyl chloride, and an acid catalyst under high temperature and pressure, and use xylene as the solvent.

Purify by dissolving in ethyl cellosolve acetate. When the sensitizer, orthonaphthoquinonediazide sulfonyl chloride, was added to the solution in an amount of 30% by weight or more, for example, 50% by weight, sufficiently large permeation characteristics were obtained. The above-mentioned A parameter was around 4. This aqueous solution was applied to a resist coated to a thickness of 1.5 μm on a substrate and a water-soluble organic film coated thereon to a thickness of 0.6 μm using a pullulan aqueous solution.
．． A pattern-forming organic film was coated and laminated to a thickness of 5 μm.

That is, as a result, a three-layer structure consisting of a normal resist, a water-soluble organic film, and the above pattern-forming organic film is formed on the substrate.

Next, a pattern forming method using the three-layer structure will be explained with reference to FIG.

1. A resist 2 is placed on a substrate 1 such as a semiconductor. Q~2.071
It is coated to a thickness of 1n (Fig. 5A). Next, a water-soluble organic film 6, for example, an aqueous solution of pullulan, which is a polysaccharide, is applied and formed for lift-off. The film thickness at this time was approximately 0.1 to 0.3 μm so as not to affect pattern formation [Fig. 5B
]. Next, after forming the novolac resin 7 containing excess orthonaphthoquinonediazide described in Example 2 to a thickness of about 0.3 to 1.0 .mu.m (FIG. 5C), blunt exposure to ultraviolet rays is carried out in a desired pattern. Next, novolak resin with excess orthonaphthoquinone diazide7. Water-soluble organic [8, resist 2 is simultaneously developed with an alkaline developer to form a pattern [6th]
Figure D]. At this time, a water-soluble organic film 6 without pattern forming ability
At the same time as the resist 2 was removed, the uppermost layer, the novolac fat 7 containing excess orthonaphthoquinone diazide, was lifted off, resulting in a pattern consisting only of the resist 2. At this time 0
．． 6 μm lines and spaces could be clearly resolved.

In carrying out the present invention, the resist 2 may be one that can be developed with an aqueous developer such as water or an alkali, and for example, a commonly used diazo positive type resist is a typical example.

Furthermore, the water-soluble organic film 6 has a bleaching and fading effect, and a Tahatern-forming organic film 5 may be used.

Effects of the Invention As described above, this invention improves the contrast by reducing the deterioration of the resolution pattern shape, which was limited by the optical system of the conventional reduction projection method, and uses a water-soluble organic film that requires fewer steps. By using this method, it is possible to make ultraviolet ray exposure finer, that is, extend its life, and it is possible to reduce the need for introducing expensive EB exposure machines and X-ray exposure machines, which is of great industrial value.

[Brief explanation of the drawing]

FIGS. 1A and 1D are cross-sectional views of the pattern forming process according to an embodiment of the present invention, FIGS. 2A to 2E are conventional contrast enhancement process flows M1, and FIGS. 4 is a transmission characteristic diagram of a patterned organic film of the present invention, and FIGS. 6A to 6D are cross-sectional views of pattern formation using a layered resist according to another embodiment of the present invention. 1...Substrate, 2...Resist (photosensitive resin), 6.7...Pattern forming organic film, 6.
...Water-soluble organic film. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 4 Exposure time 1 second) - + Figure 5 Procedural amendment document February 26, 1985 Patent Application No. 16949 2 Name of the invention Layered structure resist and pattern form using the same 4 Defense test 3
MffEyut6□ '4' Examiner ¥1
Relationship with Patent Application Address 1006 Kadoma, Kadoma City, Osaka Name (
582) Matsushita Electric Industrial Co., Ltd. Representative Akio Tanii 4 Agent 571 Address 1006 Oaza Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 5 Subject of amendment 6, Contents of amendment (1) Patent in the specification The scope of claims will be amended as shown in the attached sheet. (2) Correct "Figure 2 a" on page 7, line 7 of the specification to "Figure 2 A." (3) On page 7, line 9, “Figure 2 bJ is “Figure 2 B.”
will be corrected. - (4) Change “Figure 2 d” on page 7, line 12 to “Figure 2 D”
Correct to J. (6) On page 7, line 14, ``The above J is amended as follows.
The CEL process described in this issue also involves a complicated process in which the entire CEL film is removed with trichlorethylene and then the exposed portion of the resist underneath is removed. (6) Correct "on the register" on the 3rd line of page 11 of the statement to "on the register". Platform nine-
Insert the following sentence after 41. "When a diazo compound is used as a substance that exerts a bleaching or fading effect, it has good light absorption efficiency, high solubility in water, and a fast reaction rate. In addition, it has particularly good compatibility with pullulan. When pullulan is used as a polymer, it dissolves easily in cold water, is stable, and is easy to apply, making it extremely effective in semiconductor photolithography processes.'' (8) ``Shikatsu'' in the first line of page 17 of the same page is replaced with ``performance as a material.'' It is corrected to "excellent". Claims (1) A layered resist comprising a photosensitive resin and a layered resist formed on the photosensitive resin and having a bleaching effect or a fading effect against radiation. (2) The layered resist according to claim 1, wherein the organic film contains pullulan. A first water-soluble organic film formed on the photosensitive resin and removed by a developer of the resin; 1. A layered resist having a laminated structure comprising a second water-soluble organic film that has an action and is removed by a developer of the photosensitive resin. (4) A step of applying a photosensitive resin to a substrate, a step of forming a water-soluble organic film containing a compound having discoloration or bleaching properties on the photosensitive resin, and a step of forming a water-soluble organic film containing a compound having discoloration or bleaching properties between the photosensitive resin and the discoloration or bleaching properties. a step of selectively exposing a water-soluble organic film containing a compound with A pattern forming method characterized in that the water-soluble organic film containing the compound having color fading or bleaching properties and a part of the photosensitive resin are removed. (5) A step of applying a photosensitive resin to a substrate, a step of forming a first water-soluble organic film on the photosensitive resin, and a step of forming a second water-soluble organic film on the first water-soluble organic film. The process of
selectively exposing the second water-soluble organic film, and simultaneously developing the three-layer structure of the selectively exposed photosensitive resin and the first and second water-soluble organic films thereon; . A pattern forming method, comprising removing a portion of the first and second water-soluble organic films and the photosensitive resin.

Claims (4)

[Claims] (1) A layered resist having a laminated structure of a photosensitive resin and a water-soluble pattern-forming organic film formed on the photosensitive resin and having a bleaching or fading effect against radiation. (2) Laminated structure consisting of a water-soluble organic film formed on a photosensitive resin, and a pattern-forming organic film that is water-soluble and has a bleaching or fading effect against radiation, further formed on the water-soluble organic film. A layered resist characterized by having. (3) A step of applying a photosensitive resin to a substrate, a step of forming a water-soluble organic film containing a compound having discoloration or bleaching properties on the photosensitive resin, and a step of forming a water-soluble organic film containing a compound having discoloration or bleaching properties between the photosensitive resin and the discoloration or bleaching properties. a step of selectively exposing a water-soluble organic film containing a compound having the following: a step of simultaneously developing the two-layer structure of the selectively exposed photosensitive resin and the water-soluble organic film thereon; after the developing step, A pattern forming method characterized by removing the water-soluble organic film containing the compound having discoloration or bleaching properties. (4) a step of applying a photosensitive resin to a substrate; a step of forming a water-soluble organic film on the photosensitive resin; a step of forming a pattern-forming organic film on the water-soluble organic film; a step of selectively exposing to light, a step of simultaneously developing the selectively exposed photosensitive resin and a three-layer structure of a water-soluble organic film thereon and a pattern-forming organic film; after the developing step, the pattern-forming organic film; A pattern forming method characterized by removing the water-soluble organic film.