JPH02118655A - Contrast enhancing material to be used for forming pattern - Google Patents

Abstract

PURPOSE:To obtain a pattern forming material having high reactivity for KrF excimer laser light, etc., and providing a fine pattern having sufficiently good shape of submicron order by constituting the material of a photosensitive compd. which generates sulfonic acid by exposure, a resin, and a solvent. CONSTITUTION:Diazo groups being weak to the effect of acids cause elimination reaction efficiently by the exposure with DUV rays, when a photosensitive compd. generating sulfonic acid which is a stronger acid than carboxylic acid. Accordingly, a photosensitive compd. generating sulfonic acid in accompany with elimination of diazo groups by the irradiation with DUV rays such as KrF excimer laser light, is used. When such photosensitive compd. is used as a photosensitive agent in a contrast enhancing material for DUV(particularly, for KrF excimer laser), the material exhibits high absorption before exposure, but the absorption decreases at high speed after exposure causing discoloration, so the enhancement of contrast of an exposure part to unexposed part is attained with a small degree of exposure. Thus, a fine pattern realizing an improvement of resolution is formed.

Description

Detailed Description of the Invention Field of Industrial Application This material has a low initial transmittance to energy rays, especially far ultraviolet rays and excimer laser light, and has a bleaching effect on energy T rays, especially far ultraviolet rays and excimer laser light. The transmittance increases after complete bleaching [characteristic formula where the horizontal axis is exposure energy (3) and the vertical axis is transmittance (7), Y=AX+
If B, A tends to be large and B tends to be small],
The present invention relates to a fine pattern forming material that enables improvement in resolution compared to conventional exposure methods by exposing the resist to light through a thin film of the material after being applied onto the resist.

Conventional technology 6A-1 1983, B, F, Griffing of GE, USA
announced a method for improving the resolution and pattern shape by stacking a contrast enhancement layer that promotes the contrast of the light intensity profile on a resist for pattern formation (Contrast Enhanced Photolithography).
photolithography).

B, R, Griffin et al. ED.

EDL-4 volumes (B, F, Griffingetal
, IEEE-ED.

VOL, EDL-4), AI, Jan,
1983).

According to this announcement, the normal reduction projection method (λ: 436 nm,
It is reported that resolution of up to 0.4 prn is possible with N, A, 0.32).

As a result of the inventors' research, the characteristics of the patterned organic film for enhancing contrast can be explained as follows.

Generally, the output light intensity profile in the reduction projection method is processed by the optical lens system.

To explain, when exposing ultraviolet light through a reticle, the ideal input light intensity profile without diffraction can be said to be a perfect rectangular wave, and its contrast (C) is expressed by the following equation. At that time, the contrast C becomes 1oo%. The input waveform passes through an optical lens, and after being Fourier transformed by the transfer function of the optical lens system,
The output waveform is close to the shape of a cosine wave, and the contrast is C.
also deteriorates. This deterioration of contrast greatly affects pattern shape, such as resolution and pattern shape. By the way, the contrast required for resist pattern resolution is said to be 60% or more based on the characteristics of the resist itself, and the contrast C
If the value is less than 60%, pattern formation becomes impossible.

Therefore, in the characteristic curve of the pattern-forming organic film, in other words, in the region where the extinction time (exposure energy) is small, the transmittance to ultraviolet rays is small (the increase in min is small), and in the region where the exposure energy is large, the transmittance to ultraviolet rays is small. It has been discovered that by passing the above-mentioned output waveform through a film that tends to be large (large increase in ma!), the contrast C value tends to increase. In order to explain this more quantitatively, a report by F. H. Dill et al. (Characterization of Positive Photoresists) from IBM, USA.
Characterization of Po5it
ive Photoresist).

F, H, Dill and others IEEEE-ED, ED-22
Volume (F, H, Dill et al, IEEE-ED
, VOL, ED22), 47, Jul, 19
75), the parameters given in the exposure absorption term A of the positive resist are used. Generally, A is expressed as , and it is desirable that contrast enhancement tends to have a large A value. In order to make A tend to be large, it is necessary that d (film thickness) be thin and the ratio of T (0) (initial transmittance) and T←) (final transmittance) be large.

However, conventional contrast-enhancing materials only have 43
If the material is suitable for ultraviolet light of 6 nm, 365 nm, or 405 nm, it will have no absorption sensitivity to these wavelengths when exposed using DUV light or a KrF excimer laser of 2489/-7 nm. Not shown. Figure 3 shows the ultraviolet spectral curve of a conventional contrast-enhanced film (
It can be seen that there is no absorption in the DUV region).

FIG. 4 describes a pattern forming method using a conventional contrast-enhancing material for excimer laser exposure. A resist 2 is spin-coated on a substrate 1 (see FIG. 4(a)).
)). Next, a water-soluble contrast enhancement layer 6 is spin-coated on the resist 2 (FIG. 40)). Then, it is selectively exposed to light using an excimer laser 4 through a mask 5 using a reduction projection method (FIG. 4(C)). At this time, resist 2
A portion of the area is also selectively exposed. Finally, a normal development process is performed to remove the water-soluble contrast enhancement layer and only the light irradiated portion of the resist 2 to form a pattern 2b (FIG. 4(d)).

Problems to be Solved by the Invention However, as mentioned earlier, the conventional contrast-enhancing material has almost no transparency in the DUV region, so when this material is used, it does not show any contrast-enhancing effect. , the resist pattern 2b is the same as that in the case of normal exposure, the shape is not good, and it is not sufficient.

Accordingly, the present invention is to provide a patterned phase contrast-enhancing material that has a contrast-enhancing effect on deep ultraviolet light, particularly 248 nm excimer V-"j' light VC.

A contrast C value non-instrument material using a photosensitive compound having good contrast enhancement in the DUV region has been proposed (Japanese Patent Application No. 187133/1982). When the compound having the above-mentioned photosensitive group is exposed to DUV light, for example, KrF excimer laser, carboxylic acid is generated as the diazo group is eliminated, and the acidity of the carboxylic acid promotes the elimination action of the diazo group. The reaction mechanism is that However, since carboxylic acid has low acidity, the diazo group elimination reaction does not proceed efficiently. Therefore, the contrast-enhancing material using the photosensitized 11/, -7 metal having the photosensitive group has low sensitivity and lacks practical use.

Means for Solving the Problems In order to solve the above problems, the present invention uses a photosensitive compound that generates sulfonic acid upon elimination of a diazo group when exposed to IL) UV light such as a KrF excimer laser. It provides a contrast-enhancing material.

Effect: By using a photosensitive compound that generates sulfonic acid, which is a stronger acid than carboxylic acid, the diazo group, which is weak against acids, can be
Elimination reaction occurs efficiently by exposure to UV light. Therefore, the absorption caused by the diazo group in the DUV region is small, resulting in photobleaching.

When these photosensitive compounds are used as photosensitizers for contrast-enhancing materials for DUV (especially K r F excimer laser), they show high absorption before exposure, and after exposure, the absorption fades at a rapid rate, causing the exposed areas to fade. The contrast of the unexposed area can be improved with a low contrast, that is, the decrease in sensitivity, which is one of the drawbacks of conventional phosphorography using contrast-enhancing materials, can be suppressed.

Examples of photosensitive compounds that generate sulfonic acid upon elimination of diazo groups by DUV light include those containing 137 in the molecule, but are not limited to these.

In a photosensitive compound having these bonds, the cydiazo group is removed by DUV light exposure, and as a result, an intramolecular rearrangement reaction or a main chain cleavage reaction occurs, resulting in an o O II ll -5- group or -S - group occurs. This group indicates moisture within the contrast-enhancing material or atmospheric acidity.

Note that it is preferable to use water as a solvent for the contrast-enhancing material. This is because contrast enhancing materials using organic solvents require a process 14 to dissolve the contrast enhancing layer, and when applied directly onto the resist, the upper part of the resist dissolves and mixes with the contrast enhancing material. This is because the contrast-enhancing material film cannot be applied uniformly, and an intermediate film (for example, a film made of a pullulan aqueous solution) must be formed. In order to use water as a solvent, the photosensitive compound must also be made water-soluble. In order to make a photosensitive compound water-soluble, -8 is added in the molecule.
Possible examples include o3H group, -5o3CH3 group, pyridinium salt group, ammonium salt group, -N=N- group, but are not limited to these.

It is also desirable for the resin to be water-soluble as well. Examples include, but are not limited to, pullulan, polyvinyl alcohol, and polyvinylpyrrolidone.

EXAMPLES The present invention will be explained in more detail using Examples below, but the present invention is not limited to these Examples in the same way.

(Example 1) 16/, A reagent was prepared with the following composition and used as a contrast enhanced material for pattern formation.

Fumushiran
11 Pure water 10 A pattern forming method using a contrast enhancing material for pattern forming according to the present invention will now be described with reference to FIG. A positive resist 2 is placed on a substrate 1 such as a semiconductor.
is applied by rotation to obtain a resist film with a thickness of 1.0 μm (first
Figure (a)). After normal pre-baking, the pattern-forming contrast-enhancing material 3 of the present invention is applied by rotation (FIG. 10)).

At this time, the pattern-forming contrast-enhancing material film and the positive resist could be applied well without mixing. Next, selective exposure is performed using a KrF excimer laser 4 through a mask 5 (FIG. 1(C)). Finally, the pattern-forming contrast-enhancing material film 3 and the exposed portions of the positive resist 2 were dissolved and removed using an ordinary alkaline developer to obtain a resist pattern 2a (FIG. 1(d)). At this time, the resist batten 2a had a submicron pattern (0.4 μm line and space) with a high aspect ratio (90 degrees). In addition, the exposure amount required for pattern formation is 120
Compared to the case where the pattern was formed using only ml/ltl and resist, there was an increase of only 10q6. FIG. 2 shows this pattern-forming contrast-enhancing material at 0.00.
The UV spectral curves before and after exposure to KrF excimer laser when deposited to a thickness of 25 μm are shown, and it can be seen that the transmittance at 248 nm was 3% before exposure, but it was approximately 90% after exposure, showing a high contrast. .

(Example 2) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and an experiment similar to that in Example 1 was conducted.

Gururan Pure water C1 171, As a result, the same good results as in Example 1 were obtained.

(Example 3) A reagent was prepared with the following composition and used as a contrast contrast material for pattern formation, and the same experiment as in Example 1 was conducted.

18... As a result, good results similar to those of Example 1 were obtained.

(Example 5) A reagent was prepared with the following composition and used as a contrast engraving material for pattern formation, and the same experiment as in Example 1 was conducted.

1? Pullulan 11 pure water
1oy As a result, similar good results as in Example 1 were obtained.

(Example 4) A reagent was prepared with the following composition and used as a contrast entrainment material for pattern formation, and the same pullulan as in Example 1 was used.
12 pure water
1 (M) As a result, good results similar to those of Example 1 were obtained.

(Example 6) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

Pullulan pure water o2 19, Nipululan 1f pure water 10F As a result, good results similar to those of Example 1 were obtained.

(Example 7) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

conducted an experiment.

Pullulan 1F
Pure water 10F As a result, the same good results as in Example 1 were obtained.

(Example 9) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

Pullulan 12 Pure Water 10F As a result, the same good results as in Example 1 were obtained.

(Example 8) A reagent was prepared with the following composition and used as a contrast enhanced material for pattern formation, and the same pullulan as in Example 1 was used.
12 pure water
As a result, the same good results as in Example 1 were obtained.

(Example 10) 21. A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

O1t 7'yv5y
1F pure water 10t As a result, the same good results as in Example 1 were obtained.

(Example 11) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

0 0 1y pullulan 1f pure water
10f As a result, good results similar to those in Example 1 were obtained22,
, I got it.

(Example 12) A reagent was prepared with the following composition and used as a contrast enhanced material for pattern formation, and the same experiment as in Example 1 was conducted.

Pullulan 12 Pure Water 10F As a result, the same good results as in Example 1 were obtained.

(Example 13) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

OQ pullulan Pure water 0F 231, As a result, good results similar to those in Example 1 were obtained.

(Example 14) A reagent was prepared with the following composition and used as a contrast entrainment material for pattern formation, and the same experiment as in Example 1 was conducted.

As a result, good results similar to those of Example 1 were obtained.

(Example 16) A reagent was prepared with the following composition and used as a contrast enhancement material for pattern formation, and the same experiment as in Example 1 was conducted.

○ 0 1! il
Pullulan 12 Pure water 101 As a result, the same good results as in Example 1 were obtained.

(Example 15) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

Pullulan 12 Pure water 107 As a result, the same good results as in Example 1 were obtained.

(Example 17) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

pullulan Pure water 1g 0P 25.3. .

Pullulan 17 pure water
102 (Example 18) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

N20 II II 11 O Flurane 1f Pure water 101 As a result, the same good results as in Example 1 were obtained.

(Example 19) A reagent was prepared with the following composition and used as a contrast enhanced material for pattern formation, and the same experiment as in Example 1 was conducted.

Pullulan 12 Pure water 1 (M) As a result, the same good results as in Example 1 were obtained.

(Example 20) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

O Pullulan 1g Pure Water ICM As a result, the same good results as in Example 1 were obtained.

(Example 21) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

27 l< O.

CH3 Pullulan 1 g Pure water 1 ot As a result, the same good results as in Example 1 were obtained.

(Example 22) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

CH3-CH2-8o3C) 1y pullulan
1f pure water
10? As a result, good results similar to those of Example 1 were obtained.

(Example 23) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and an experiment similar to Example 1 was conducted.

Pullulan 12 Pure Water 10F As a result, the same good results as in Example 1 were obtained.

(Example 24) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

t 29, -3-.

Pullulan 1f Pure water 10f As a result, the same good results as in Example 1 were obtained.

(Example 26) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

Pullulan 1F Pure water 10F As a result, the same good results as in Example 1 were obtained.

(Example 26) A reagent was prepared with the following composition and used as a contrast secondary material for pattern formation, and the same experiment as in Example 1 was conducted.

30 l. CH-CH-8o 0111 Pullulan 1f Pure water 10f As a result, the same good results as in Example 1 were obtained.

(Example 27) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

pullulan Pure water f 31 /, -1 As a result, good results similar to those of Example 1 were obtained.

(Example 28) A reagent was prepared with the following composition and used as a pattern-forming Con I-last enhanced material, and the same experiment as in Example 1 was conducted.

Pullulan 12 Pure water 1of As a result, the same good results as in Example 1 were obtained.

(Example 30) A reagent was prepared with the following composition and used as a contrast enhanced material for pattern formation, and the same experiment as in Example 1 was conducted.

Pullulan 11 Pure Water 105' As a result, the same good results as in Example 1 were obtained.

(Example 29) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

0 0 1' Pullulan
12 pure water
10F As a result, good results similar to those of Example 1 were obtained.

(Example 31) A reagent was prepared with the following composition and used as a contrast contrast material for pattern formation, and the same experiment as in Example 1 was conducted.

The same experiment as in Example 1 was conducted using 33, , = contrast enhanced material.

Pullulan 11 Pure water 10S' As a result, the same good results as in Example 1 were obtained.

(Example 32) A reagent was prepared with the following composition and used as a contrast-enhancing material for pattern formation, and the same experiment as in Example 1 was conducted.

0 0 1' Pullulan 12 Pure water
102 As a result, good results similar to those of Example 1 were obtained.

(Example 33) Prepare a reagent with the following composition and use Cobble Run 12 pure water for pattern formation.
10f As a result, good results similar to those of Example 1 were obtained.

In this example, the resin was limited to pullulan and the solvent was limited to pure water, but when the solvent is pure water, any resin may be used as long as it is water-soluble, such as polyvinyl alcohol,
Polyvinylpyrrolidone, polyethylene glycol, polyethylene oxide, etc. may also be used. Also, any solvent may be used as long as the photosensitive compound or resin can be used as a solvent.

Some solvents dissolve the resist when forming a film on the resist, but contrast enhancement materials for pattern formation using these solvents are used to dissolve the resist 36/, - before forming a contrast enhanced film.

The present inventors have confirmed that it is sufficient to form a water-soluble organic thin film such as pullulan on the strip.

Effects of the Invention The present invention provides a contrast-enhancing material for pattern formation that exhibits excellent reactivity to, for example, 248 nm KrF excimer laser light. When applied to a contrast enhancement layer for deep UV (deep UV) exposure, fine patterns with good shapes on the order of submicrons can be easily obtained, so it is of great value for the formation of ultra-fine patterns in the semiconductor industry.

[Brief explanation of the drawing]

FIG. 1 is a process cross-sectional view of a pattern forming method using a contrast-enhancing material for pattern formation according to an embodiment of the present invention, and FIG. Ultraviolet spectral curve diagrams before and after laser exposure, Figure 3 is a conventional contrast-enhancing material for pattern formation (7) K r
F Ultraviolet ray spectral curve diagrams before and after excimer laser exposure, FIG. 4 is a process cross-sectional view of a pattern forming method using a conventional contrast-enhancing material for forming battens. 1...Substrate, 2...Positive resist,
3... Contrast enhancement material film for pattern formation, 4... KrF excimer laser, 5...
...Mask, 2a...Resist pattern.

Claims (16)

[Claims] (1) A contrast-enhancing material for pattern formation comprising a photosensitive compound and a resin in which sulfonic acid is generated as a diazo group is eliminated by KrF excimer laser exposure, and a solvent capable of dissolving the compound and resin. (2) The contrast-enhancing material for pattern formation according to claim 1, wherein the photosensitive compound has at least one ▲a mathematical formula, a chemical formula, a table, etc.▼bond. (3) The contrast enhancement for pattern formation according to claim 1 or 2, characterized in that the photosensitive compound has at least one ▲a mathematical formula, a chemical formula, a table, etc.▼bond. material. (4) Pattern formation according to claim 1 or 2, characterized in that the photosensitive compound has at least one ▲a mathematical formula, a chemical formula, a table, etc.▼bond. Contrast enhancing material. (5) Pattern formation according to claim 1 or 2, characterized in that the photosensitive compound has at least one ▲ mathematical formula, chemical formula, table, etc. ▼ bond. Contrast enhancing material. (6) Pattern formation according to claim 1 or 2, characterized in that the photosensitive compound has at least one ▲a mathematical formula, a chemical formula, a table, etc.▼bond. Contrast enhancing material. (7) The contrast-enhancing material for pattern formation according to claim 1 or 2, wherein the photosensitive compound has the following structure. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R_1 and R_2 are substituents) (8) The contrast-enhancing material for pattern formation according to claim 1 or 2, wherein the photosensitive compound has the following structure. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R_1 and R_2 are substituents) (9) The contrast-enhancing material for pattern formation according to claim 1, wherein the photosensitive compound has at least one ▲a mathematical formula, a chemical formula, a table, etc. ▼bond. (10) Pattern formation according to claim 1 or 9, characterized in that the photosensitive compound has at least one ▲a mathematical formula, a chemical formula, a table, etc.▼bond. Contrast enhancing material. (11) Pattern formation according to claim 1 or 9, characterized in that the photosensitive compound has at least one ▲a mathematical formula, a chemical formula, a table, etc.▼bond. Contrast enhancing material. (12) Pattern formation according to claim 1 or 9, characterized in that the photosensitive compound has at least one ▲ mathematical formula, chemical formula, table, etc. ▼ bond. Contrast enhancing material. (13) Pattern formation according to claim 1 or 9, characterized in that the photosensitive compound has at least one ▲a mathematical formula, a chemical formula, a table, etc.▼bond. Contrast enhancing material. (14) The contrast-enhancing material for pattern formation according to any one of claims 1 to 13, wherein the photosensitive compound is water-soluble. (15) The contrast-enhancing material for pattern formation according to any one of claims 1 to 14, wherein the resin is water-soluble. (16) The contrast-enhancing material for pattern formation according to any one of claims 1 to 15, wherein the solvent is water.