JPH07134410A - Resist material - Google Patents

Abstract

PURPOSE:To provide a resist material capable of improving dimensional uniformity and resolution by eliminating the T-shaped top shape of a positive resist or the round top shape of a negative resist, which arises along with the disappearance of acid on the surface of the resist, in the chemically amplifying resist. CONSTITUTION:The chemically amplifying resist contains an acid generating agent generating an acid dimer or polymer by the light irradiation though an acid generating agent contained in the conventional chemically amplifying resist generates an acid monomer. Then, even if one of the acids is neutralized by a base entering from air, the acid catalytic reaction is not impaired because at least one of the acids remains. Since the acids are placed close to each other eve if two or more acids are present, the acid catalytic reaction is not accelerated too. The dimensional accuracy and the process margin are increased because the diffusion is suppressed by polymerizing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist material used in a lithography process in manufacturing a semiconductor device, and more particularly to a chemically amplified resist material excellent in pattern resolution.

[0002]

2. Description of the Related Art In recent years, the demand for fine pattern formation has increased with the increasing integration of LSIs. Conventionally, the main focus of this fine pattern forming technology (lithography technology) is an exposure apparatus that uses g-line or i-line of a mercury lamp, and an ultraviolet exposure technology that combines a stepper and a novolac-based resist. And the improvement of overlay accuracy, etc.), the resolution of novolac resists has been improved. However, when the exposure wavelength is shortened in order to further improve the resolution (eg, KrF excimer laser light, deep ultraviolet light such as mercury arc lamp light around 250 nm), novolac-based resists have large absorption of resin and naphthoquinonediazide photosensitizer. A rectangular resist shape cannot be obtained (tapered).
In addition, the sensitivity of novolac resist (usually 100 mJ-20
At 0 mJ / cm ² , the light intensity of the narrow band KrF maxima laser light source is weaker than that of g and i lines (1/5 to 1/1).
10) Exposure time is long. Chemically amplified resists have been proposed to overcome this situation [references
H. Ito and CW Wilson, ACS Symposium Series, 242,
pp.11 (1984).]. Since this type of resist utilizes the catalytic reaction of the acid generated from the photosensitive acid generator, a small amount of acid concentration is required (on the order of μmole / gram), and therefore a highly sensitive resist design is possible. The resist shape can be greatly improved by selecting a low concentration acid generator and a highly transparent resin.

FIG. 4 shows an example of an acid-catalyzed reaction of a chemically amplified negative resist composed of PVP (polyvinylphenol resin) and a melamine crosslinking agent, and FIG. 5 shows an acid catalyzed reaction of a chemically amplified positive resist composed of tert-butoxycarbonyloxystyrene. It is a thing. [Reference JWThackeray et al.,
Proc. SPIE, 1086, pp.34 (1989), CGWilson et a
l., J. Electrochem. Soc., 133, pp.181 (1986).]. The negative resist is composed of three components of polyvinylphenol resin, melamine cross-linking agent, and acid generator, and the acid accelerates the cross-linking reaction to insolubilize the exposed area. On the other hand, in the case of positive type, tert-
Resin protected with butoxycarbonyl group and acid generator 2
It is composed of components, and the protective group is removed by acid to make it soluble in an alkaline developer. FIG. 6 shows a conventionally used acid generator. That is, as various onium salts, there are benzenediazonium salts, diphenyliodonium salts, and triphenylsulfonium salts (wherein M = As, S
b, P), and 2,4-ditrichloromethyltriazine derivative, 2,6-dinitrobenzyl tosylate, p-nitrobenzyl-9,10-diethoxyanthracene 2-sulfonate as an organic acid generator. It is shown. All acid generators generate strong acid by photoexcitation reaction, but both are acid monomers [Reference T.
X.Neeran et al., Proc. SPIE, 1086, pp.2 (1989). H.
Ito, Proc, SPIE, 920, pp.33 (1988) .A. Bruns, Micro
electronic Eng., 6, pp. 467 (1987). M. Nishiki et a
l., 1st Micro Process. Conference, pp.62 (1988).]

[0004]

Although the above-mentioned conventional chemically amplified resists have greatly improved sensitivity and resolution, there is a problem that the negative top portion of the resist shape is round and the positive shape tends to be T-shaped. was there. This occurs because a small amount of acid generated by light irradiation disappears in the resist surface area by baking treatment or basic substances (amines etc.) in the air [Reference SA MacDonald et al.,
Proc. SPIE, 1466, pp.2 (1991)]. Therefore, not only the resist shape is deteriorated, but also dimensional uniformity and resolution are deteriorated. Further, in particular, in order to reduce the influence of the external environment such as a basic substance in the air, a method of applying a protective film on the resist has been attempted. This method is certainly effective for shape stability, but on the other hand, it complicates the lithography process and tends to form a resist residue by forming a mixing layer at the interface between the protective film and the resist.

[0005]

[Means for Solving the Problems]

[Purpose] It is an object of the present invention to provide a resist material which does not deteriorate the resist shape or decrease the resolution when a chemically amplified resist is used for forming a fine pattern.

[Means] The chemically amplified resist material of the present invention uses, as an acid generator, an organic material capable of forming an acid dimer or an acid multimer of more than that. Next, the principle will be described. FIG. 1 shows an example of an acid generator that generates an acid dimer. These materials can be synthesized by using, as a starting material, a dimer (synthesized by condensation reaction or the like) similar to the starting material of the acid generator described in FIG. A plurality of acid-generating groups may be added to a polymer material having a relatively low molecular weight. Since the two acidic groups in the acid dimer are bound and exist close to each other, the efficiency of the acid-catalyzed reaction is almost the same as that of the monomer. FIG. 1 is an example of an acid generator that generates an acid dimer. (A) is di (2,6-dinitrobenzyloxysulfonylbenzene) alkylene, (b) is
Di (2,6-dinitrobenzyloxysulfonyl) phenylene, (c) is di (2,6-dinitrobenzyloxycarbonyl) alkylene, (d) is 2,6-di (4
FIG. 2 shows a photoexcitation reaction of -nitrobenzyloxysulfonyl) -9,10-dialkylanthracene.
In these formulas, R _{1 and} R ₂ are alkyl groups connecting two acid generating parts and have an arbitrary carbon chain length. R ₃ and R ₄ represent a substituent such as an alkyl group or an alkoquine group. On the other hand, even if a basic substance such as an amine is mixed, it is rare that two acidic groups are simultaneously neutralized. Therefore, even if one of them is neutralized, the efficiency of the catalytic reaction is hardly affected, and the surface effect resulting from the disappearance of the acid in the resist surface region can be significantly reduced. Further, since the molecular weight generally increases in the case of a multimer, a bake treatment (normal post-exposure bake treatment, Post Exposure Bake (PE
Even if the treatment (B) is abbreviated), molecular diffusion can be suppressed, so that dimensional accuracy can be ensured. For the same reason, dripping of the resist pattern (due to acid diffusion and catalytic reaction at room temperature) which tends to occur when left for a long time after exposure can be suppressed and the process margin is increased.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. [Example 1] The characteristics of the resist used were negative and consisted of three components: acid generator-crosslinking agent-resin. However, the acid generator is a substance capable of generating a dimer acid. Specifically, for example, the material shown in FIG. 1A is used as the acid generator, the melamine derivative is the crosslinking agent, and the PVP (polyvinylphenol resin) is the resin.
Of the three components of. FIG. 2 shows the results of applying the resist material of the present invention to the formation of a fine polycrystalline silicon gate pattern of a MOS transistor, but the basic process is the same as that of a normal acid catalyst resist. In FIG. 2A, a gate oxide film 202 is formed on a silicon substrate 201 by thermal oxidation, a polycrystalline silicon film 203 is further grown thereon by chemical vapor deposition, and a negative resist 204 is applied with the acid catalyst of the present invention. Show the appearance. Then, in order to form a gate polycrystalline silicon electrode, the resist 204 is irradiated with excimer laser light (FIG. 2B).

After that, a heat baking treatment is performed at 130 to 160.
It is carried out at 30 ° C. for about 3 seconds to 3 minutes to cause the acid-catalyzed crosslinking reaction only in the mask openings (FIG. 2C). At that time, in a chemically amplified resist that generates an ordinary acid monomer, in order to shorten the time until the bake treatment and reduce the influence of the base mixed in from the air, for example, a combination of an exposure device and a developing device, New measures such as the installation of a shield function to separate the wafer from the external environment are required. On the other hand, in the resist which generates the acid dimer of the present invention, since it is not easily affected by the external environment, ordinary cleaning measures are sufficient, and the acid diffusion is small even if the time until baking is long, It is not always necessary to connect the exposure device and the development device. Next, tetramethylammonium hydride (TM
When developed with an alkaline developer such as AH), a resist pattern 208 having excellent dimensional controllability and no resist scum as shown in FIG. 2D is obtained. Finally, using the resist pattern 208 as a mask, the polycrystalline silicon 203 is
F _4, CCl ₂ F _2, or anisotropically etched by reactive gas plasma such as HB _r, the gate electrode is formed by removing the resist.

Example 2 Next, the result of applying the present invention to a positive type resist will be described (FIG. 3). Figure 3 (a)
Is the same as in FIG. Then, excimer laser light is irradiated (FIG. 3B). Also in this case, as in the case of the negative type, even if a basic substance is mixed in from the outside, the effective acid concentration that regulates the catalytic reaction remains unchanged. Therefore, the post exposure bake process is 1
By performing the treatment at 30 to 160 ° C. for about 0.5 to 3 minutes, it is possible to sufficiently remove the protective group that suppresses the alkali solubility of the resin (FIG. 3 (c)). Next, resist development is performed with an alkali developing solution to obtain a vertical resist pattern 308 as shown in FIG. Finally, the polycrystalline silicon film is etched using the resist as a mask to form a gate electrode. Although only the formation of the fine gate electrode has been described above, it can be applied to the formation of other fine resist patterns such as a wiring pattern and a contact hole pattern.

[0010]

As described above, according to the present invention, when a chemically amplified resist containing an acid generator capable of generating a multimeric acid is applied to fine pattern formation, the resist top shape is rectangular and the external environment ( It is possible to form a resist pattern that is strong against a basic substance in the air) and to suppress the resist dimension variation.

[Brief description of drawings]

FIG. 1 is an acid generator that generates an acid dimer.

FIG. 2 is a schematic diagram of a negative resist material of the present invention
FIG. 7 is a cross-sectional view showing a step of forming a fine polycrystalline silicon gate pattern of a transistor.

FIG. 3 is a schematic diagram of a MOS using the positive resist material of the present invention.
FIG. 7 is a cross-sectional view showing a step of forming a fine polycrystalline silicon gate pattern of a transistor.

FIG. 4 is a diagram showing an example of an acid-catalyzed reaction of a conventional chemically amplified negative resist.

FIG. 5 is a diagram showing an example of an acid-catalyzed reaction of a conventional chemically amplified positive resist.

FIG. 6 is a view showing an acid generator (which generates an acid monomer) conventionally used in a chemically amplified resist.

[Explanation of symbols]

201,301 Silicon substrate 202,302 Gate oxide film 203,303 Polycrystalline silicon film 204 Chemical amplification type negative resist containing acid generator that generates acid dimer 304 Acid generator that generates acid dimer Chemical amplification type positive resist contained 205,305 Excimer laser light 206,306 Exposure area 207 Crosslinking area of negative resist 307 Protective group elimination area of positive resist 208,308 Resist pattern after development

Claims (2)

[Claims] 1. A chemically amplified resist in which the solubility of the resist is changed by utilizing a catalytic reaction of an acid generated from a photosensitive acid generator, characterized by containing an acid generator for generating an acid multimer. Chemically amplified resist. 2. An acid generator for generating an acid multimer is di (2,6-dinitrobenzyloxysulfonylbenzene) alkylene, di (2,6-dinitrobenzyloxysulfonyl) phenylene, di (2,6-). Dinitrobenzyloxycarbonyl) alkylene or 2,6-di (4-nitrobenzyloxysulfonyl) -9,10-
The chemically amplified resist according to claim 1, which is any one of dialkylanthracenes.