JPH061382B2 - Radiation sensitive material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a material for lithography, and more specifically, it forms a conventional radiation-sensitive resist layer as a lower layer on a substrate, and then forms the same as an upper layer. By forming a radiation-sensitive layer made of the radiation-sensitive material of the invention and irradiating with radiation through the radiation-sensitive layer of the upper layer, the pattern conversion difference of the lower resist layer, the resist profile, the resolution,
It relates to a radiation-sensitive material for improving focus tolerance.

[Prior Art] In recent years, with the miniaturization of integrated circuits, the dimensions of resist patterns required at the time of manufacturing integrated circuits have become finer and finer, and strict control of dimensional accuracy has been required. In order to meet this demand, development of a resist pattern forming technique capable of forming a high-resolution resist pattern and maintaining dimensional accuracy even when the manufacturing process changes conditions is in progress.

As such a resist pattern forming technique, for example, a contrast enhancing lithography method (hereinafter referred to as “CEL method”) has been proposed.

This CEL method is based on BF Griffin (B.F.G.
riffing) et al. [IEEE, Electron D
device Letters, Vol. EDL-4,
(1) 14 (1983)], wherein a radiation-sensitive layer containing a radiation-fading substance (hereinafter, simply referred to as "radiation-sensitive layer") is provided on the resist layer before irradiation with radiation. It is a method of irradiating the lower resist layer with radiation through the radiation sensitive layer.

The feature of this method is to enhance the contrast of the irradiance with respect to the resist layer by irradiating the radiation through the radiation sensitive layer.

That is, since the amount of fading of the radiation sensitive layer is small in the shadow portion where the radiation dose is relatively small, and the amount of fading of the radiation sensitive layer is large in the highlight portion where the radiation dose is large, the highlight portion is larger than the shadow portion. The amount of transmitted radiation is relatively increased, and the contrast of irradiance is enhanced for the resist layer.

As described above, the CEL method is simple and easy because a high-resolution resist pattern with enhanced contrast can be obtained only by adding a step of forming a radiation-sensitive layer on the resist to the current lithography method. As a radiation fading substance used in the CEL method, for example, JP-A-59-59
An aryl nitrone compound described in JP-A-104642, a photosensitive diazonium salt described in JP-A-60-238829, and the like have been proposed.

However, although the former aryl nitrone compound has a large contrast enhancing effect, since the compound is soluble only in an organic solvent such as toluene, the lower resist layer contains, for example, a novolac resin as a main component and an alkaline aqueous solution is developed. When using a normal positive resist as a liquid, an organic solvent such as toluene dissolves the resist layer when forming the radiation sensitive layer, and a slight mutual dissolution layer is formed between the upper and lower layers, resulting in a resist pattern. It causes to reduce the profile, resolution, etc.

On the other hand, the latter photosensitive diazonium salt is water-soluble, and when used as an aqueous solution, the above problems do not occur, but when it is used as a radiation-sensitive material, it is generally used as an aqueous solution of the photosensitive diazonium salt. Since storage stability is poor,
It is difficult to put it to practical use.

[Problems to be solved by the invention]

The present invention solves the above-mentioned problems and, when used in the CEL method, can improve the pattern conversion difference of resist, the resist profile, the resolution, and the focus tolerance, and provides a radiation-sensitive material excellent in storage stability. The purpose is to provide.

[Means for solving problems]

That is, the present invention provides a radiation-sensitive material comprising a water-soluble radiation-sensitive quinonediazide compound and a water-soluble polymer compound as main components.

Hereinafter, the present invention will be described according to constituent elements.

(A) Water-soluble radiation-sensitive quinonediazide compound The water-soluble radiation-sensitive quinonediazide compound used in the present invention is used as the photofading substance.

The water-soluble radiation-sensitive quinonediazide compound used in the present invention is not particularly limited, and examples thereof include a water-soluble 1,2-quinonediazide compound and a water-soluble 1,3-quinonediazide compound.

Particularly preferable examples include water-soluble radiation-sensitive quinonediazide compounds represented by the following general formulas (I) to (III).

(In the formula, A is Or , M is monovalent such as Na ⁺ , K ⁺ , Ca ²⁺ or 2
Indicates a valent metal ion or ammonium ion. ) IN FORMULA, A AND M IS THE SAME AS GENERAL FORMULA (I). ] IN FORMULA, A AND M IS THE SAME AS GENERAL FORMULA (I). Specific examples of the compound represented by formula (I) include the following.

Further, as a specific compound represented by the general formula (II),
For example, the following can be mentioned.

Furthermore, as specific compounds represented by the general formula (III), for example, the following can be mentioned.

These water-soluble radiation-sensitive quinonediazide compounds are 1
They can be used alone or in combination of two or more.

(B) Water-soluble polymer compound Examples of the water-soluble polymer compound include natural materials such as celluloses such as hydroxypropyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polysaccharides such as casein, gelatin, shellac, and pullulan. Polymer compounds, water-soluble polymer compounds derived from the natural polymer compounds, polyvinyl alcohol, polyvinylpyrrolidone, pyracrylic acid, sodium polyacrylate, ammonium polyacrylate, polymethacrylic acid,
Polyammonium methacrylate, polymethyl vinyl ether, methyl vinyl ether, maleic anhydride polymer,
Examples thereof include synthetic polymer compounds such as polystyrene sulfonic acid, sodium polystyrene sulfonate, and copolymers containing structural units of these polymers as copolymerization components.

These water-soluble polymer compounds may be used alone or in combination of two or more.

The weight average molecular weight of these water-soluble polymer compounds is not particularly limited, but is usually 5,000 to 50,000.
It is 0, preferably 10,000 to 300,000. CEL when the molecular weight of the water-soluble polymer compound is less than 5000
When applied as a solution on the resist layer in the method,
The coating film-forming ability is poor, while when it exceeds 500000, the solubility in water or water containing a water-soluble organic solvent described later is deteriorated, and when the lower resist layer is developed, the upper radiation-sensitive layer is the resist layer. It may be difficult to be removed from above, which may deteriorate the developability.

The radiation-sensitive material of the present invention comprises (i) a water-soluble radiation-sensitive quinonediazide compound and (b) a water-soluble polymer compound, the proportion of which is water-soluble with respect to 100 parts by weight of the water-soluble radiation-sensitive quinonediazide compound. 100 to 10,000 parts by weight, and particularly preferably 200 to 5,000 parts by weight of the organic polymer compound are used. If the amount of the water-soluble polymer compound used is too small, the film becomes rough when the coating film of the radiation-sensitive material is formed, while if it is too large, the intended effect of enhancing the irradiance contrast is weakened.

The radiation-sensitive material of the present invention comprises (i) a water-soluble radiation-sensitive quinonediazide compound and (b) a water-soluble polymer compound dissolved in a suitable solvent, and the solid content concentration is preferably 1 to 30% by weight, particularly preferably It is adjusted to 2 to 20% by weight.

As the solvent used at this time, water or water containing a water-soluble organic solvent (hereinafter, referred to as “aqueous solvent”) is preferably used.

In the case of water containing a water-soluble organic solvent, water is preferably 5
It is desirable to contain 0% by weight or more, particularly preferably 80% by weight or more. Examples of the water-soluble organic solvent used here include alcohols such as methanol, ethanol, n-propanol and i-propanol, polyols such as glycerin, ethylene glycol, diethylene glycol and triethylene glycol, and cyclics such as tetrahydrofuran and dioxane. Mention may be made of ethers and ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone.

When preparing the radiation-sensitive material of the present invention, a surfactant can be added to improve its coatability. Specific examples of the surfactant used here include, for example, Kao Soap Co., Ltd., Emulgen, Leodol, Emazole, Exel, Emanone, Amate,
Acetamine, eutamine, sanizole, amphitrol;
Examples include Nippon Oil & Fats Co., Ltd., Nissan Nonion, Nissan Cation, Nissan Elegan, Nissan Pronone; Toho Chemical Industry Co., Ltd., Sorbone. Further, a defoaming agent or the like may be added to the radiation-sensitive material of the present invention.

The amount of these additives added is preferably 1 to 100,000 ppm, particularly preferably 10 to 50,000 ppm, based on the total weight of the solid content of the radiation-sensitive material.

The radiation-sensitive material of the present invention is usually spin-coated using a spin coater or the like on a resist layer formed on a substrate such as a silicon wafer or glass, and usually at room temperature to 1
Heat drying at 30 ° C., preferably room temperature to 110 ° C. At this time, the dry film thickness of the radiation sensitive layer made of the radiation sensitive material is usually 0.05 to 2 μm, and if the dry film thickness is less than 0.05 μm, pinholes are generated and a resist pattern obtained after development is obtained. However, if the dry film thickness exceeds 2 μm, the radiation dose for forming the resist pattern must be greatly increased.

The unirradiated resist layer coated with the radiation-sensitive material as an upper layer is then irradiated with radiation, and examples of irradiation methods include reduction projection irradiation method, reflection projection irradiation method, and contact irradiation method. After irradiation with radiation, the radiation-sensitive material is usually dissolved and removed with an aqueous solvent used as a solvent, or when the developing solution for the resist layer as the lower layer is an alkaline aqueous solution, the developing solution or its diluting solution. After that, the lower resist layer is developed by a conventional method.

As the lower layer resist to which the radiation-sensitive material of the present invention can be applied, for example, a positive type resist comprising a 1,2-quinonediazide compound and a novolac resin and / or polyhydroxystyrenes; an azide compound and a novolac resin and / or Negative resists composed of polyhydroxystyrenes; negative resists composed of azide compounds and cyclized rubber; negative resist composed of cresol novolak resins and / or alkali soluble resins such as polyvinylphenol and azide compounds. Of these, a positive resist containing a 1,2-quinonediazide compound, a novolac resin and / or polyhydroxystyrenes is particularly preferable. Specific examples of these resists include PFR3000 series, PFR33 manufactured by Nippon Synthetic Rubber Co., Ltd.
00 series, PFR3600 series, PFR700
0 series, PFRD70 series, CIR700 series and the like.

A transparent intermediate layer which is incompatible with the resist layer and the radiation sensitive layer may be provided between the lower resist layer and the upper radiation sensitive layer of the present invention. The intermediate layer is a polymer compound film transparent to radiation. In order to provide this intermediate layer, an organic solvent solution of the polymer compound is applied to the lower resist layer to give a dry film thickness of 0.05 to
It may be applied by spin coating so as to have a thickness of 0.5 μm, preferably about 0.05 to 0.2 μm.

Examples of the polymer compound for forming such an intermediate layer include cyclized rubber, polystyrene, poly-α-methylstyrene and the like.

When the intermediate layer is provided, the radiation-sensitive layer and the intermediate layer may be sequentially peeled off and removed after irradiation with radiation, and then the resist layer may be developed by a conventional method.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples.
The invention is not limited to these examples.

Example 1 After a resist (PFR3003A manufactured by Nippon Synthetic Rubber Co., Ltd.) containing a novolac resin and a 1,2-quinonediazide compound as a main component was spin-coated on a silicon wafer, 90
It was dried for 2 minutes on a hot plate kept at ℃ to form a resist layer having a film thickness of 1.2 μm. Then, the radiation-sensitive material of the present invention having the following formulation was spin-coated on the resist layer so that the dry film thickness was 0.23 μm, and dried at 90 ° C.

Formulation 1,2-naphthoquinonediazide-5-sodium sulfonate; 0.7 g Pullulan (manufactured by Hayashibara Biochemical Research Institute); 0.6 g Polyvinylpyrrolidone; 0.4 g Water; 9.0 g With respect to the wafer thus obtained, 20 μm.
A reticle having line and space patterns (1L / 1S pattern) of 12 μm, 10 μm, 8 μm, and 6 μm was used, and a g-line stepper (NA = 0.
28, reduction ratio 1/10). The exposure dose at this time was the exposure dose for accurately forming a line-and-space pattern in which the development resist pattern was 1.2 μm at equal intervals. Then, the radiation sensitive layer was removed using a positive resist developing stream PD523 (manufactured by Japan Synthetic Rubber Co., Ltd.) containing tetramethylammonium hydroxide as a main component, and development was carried out at the same time to obtain a resist pattern.

The pattern conversion difference of the obtained resist pattern was measured using a scanning electron microscope. The results are shown in Fig. 1.

As a result, it was found that a resist pattern having a good pattern conversion difference can be obtained by using the radiation-sensitive material of the present invention. In addition, since the radiation sensitive layer and the resist layer are not compatible with each other, a good resist profile was obtained.
Furthermore, even when the radiation-sensitive material of the present invention was stored at room temperature for 3 months, no foreign matter was generated, and the radiation-sensitive material was not deteriorated in performance.

Comparative Example 1 In Example 1, 1,2-naphthoquinonediazide-5
2,5-diethoxy-4 instead of sodium sulfonate
-Morpholinobenzenediazonium chloride 1/2
A resist pattern was prepared in the same manner as in Example 1 except that 0.65 g of zinc chloride double salt was used, and the pattern conversion difference was measured.

The results are shown in FIG. From FIG. 1, in this comparative example,
The difference in pattern conversion is inferior to that of Example 1 using the radiation-sensitive material of the present invention, and the obtained resist pattern is 1/10 of the line-and-space pattern of the reticle, especially in the case of larger than 1.2 μm. It turned out that it will be smaller than the size of. Further, when the radiation-sensitive material of this comparative example was stored at room temperature, generation of foreign matter was observed after only one day, and the performance as the radiation-sensitive material was also deteriorated.

〔The invention's effect〕

The radiation-sensitive material of the present invention has excellent storage stability, which leads to improvement in yield and is preferable in the manufacturing process of integrated circuits. Further, the radiation-sensitive layer is coated on a conventional resist layer to form a radiation-sensitive layer, and the radiation-sensitive layer By irradiating radiation through the resist, it is possible to improve the pattern conversion difference of the resist, the resist profile, the resolution, and the focus tolerance, and as a result, it is possible to perform highly accurate processing by lithography.

[Brief description of drawings]

FIG. 1 is a correlation diagram of the resist pattern size and the 1/10 size of the line-and-space pattern of the reticle.

Claims (1)

[Claims] 1. A radiation-sensitive material comprising a water-soluble radiation-sensitive quinonediazide compound and a water-soluble polymer compound as main components.