JPH01161336A - Silicon-containing resist - Google Patents

Abstract

PURPOSE:To improve oxygen resistant RIE and sensitivity and to enable alkaline development by constituting the title resist of an alkali-soluble resin contg. silicon, naphthoquinediazide contg. silicon and photosensitive agent selected from azide contg. silicon or specific compd. CONSTITUTION:This resist is constituted of the alkali-soluble resin contg. silicon, the naphthoquinediazide contg. silicon and the photosensitive agent selected from the azide contg. silicon or the compd. expressed by formula I. In formula I, R1-R4 denote hydrogen, substd. or unsubstd. alkyl group of 1-10C, substd. or unsubstd. aryl group or substd. or unsubstd. silyl group. The extremely high oxygen resistant RIE characteristic is thereby obtd. and the good mask effect to the dry etching of the flattened layer of the lower layer by oxygen plasma is exhibited. In addition, the alkali developability is improved and the higher sensitivity is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a silicon-containing resist, and particularly to a silicon-containing resist used for manufacturing semiconductor devices, photomasks, and the like.

(Prior technology) As a microfabrication technology for manufacturing high-density integrated circuits, magnetic bubble elements, and optical components, ionizing radiation such as electron beams, X-rays, and ion beams, or short wavelength ultraviolet rays are used in parallel with photolithography technology lithography is being put into practical use. In particular, the latter lithography technique is indispensable for microfabrication of about 0.5 μm or less.

In recent years, as semiconductor devices have become three-dimensional, there has been a tendency to form resist patterns on semiconductor substrates with considerable steps and to perform microfabrication. In such a case, it is necessary to increase the resist film thickness to some extent, but increasing the resist film thickness causes the problem of a decrease in resolution.

For this reason, a thick planarization layer is formed on the semiconductor substrate, several layers including a thin resist film are formed on top of this, and the resist pattern on the upper layer is sequentially transferred to the lower layer by dry etching. , a multilayer process that forms a resist pattern with a high shape ratio is being used. As a normal multilayer resist, a three-layer system is most often used, in which an intermediate layer having oxygen plasma resistance is formed on a flattening layer, and a thin resist film is formed on this intermediate layer. However, this method has the problem that the drying process must be repeated several times to transfer the resist pattern, making the process extremely complicated.

Therefore, a two-layer resist process is being developed in which a resist film that itself has oxygen plasma resistance is formed on the planarization layer. As a resist having such oxygen plasma resistance, chloromethylated polydiphenylsiloxane and the like have been known. However, since these resists are composed of polymers of monomers having a structure in which a large amount of silicon is introduced into benzene nuclei, an ordinary organic solvent must be used as a developer in the development step after exposure. As a result, the solvent permeates into the pattern formed one time after development, causing the pattern to swell, making it difficult to form a fine pattern with high precision.

(Problems to be Solved by the Invention) The present invention has been made in order to solve the above-mentioned conventional problems. This is what we are trying to provide.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a silicon-containing alkali-soluble resin, a silicon-containing naphthoquine diazide, a silicon-containing azide, or a compound represented by the following general formula (I). A silicon-containing resist characterized by comprising a photosensitizer selected from the following.

Responsibility.

However, R1 to R4 in the above general formula (I) represent hydrogen, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group, or a substituted or unsubstituted silyl group.

Examples of the silicon-containing alkali-soluble resin include, but are not particularly limited to, polymers represented by [A] in Table 1 listed below, which are obtained by introducing silicon into the phenyl group of novolak resin, novolak resin, vinylphenol resin, Polymers represented by [B] in Table 1 in which silicon is introduced into a portion of the OH of propenylphenol resin through ether or ester groups, and [B] in Table 1 in which silicon is introduced into the alkyl group of novolak resin. Polymers represented by [C], IDs in Table 1 with phenol groups introduced into the siloxane bonds]
Polymers typified by , acrylic resins, methacrylic resins and methacrylic resins in which silicon is introduced, typified by the first surface [E] of the same, etc. can be mentioned.

Examples of the silicon-containing naphthoquinone diazide and silicon-containing azide include those shown in Table 2 below.

Substituents to the alkyl groups as R1-R4 introduced into the above general formula (I) include, for example, a halogen group, an unsaturated group, a carbonyl group, a carboxyl group, a nitrile group, a thioether group, a thioester group, etc. can. An aryl group as R1-R4 introduced into the general formula (I),
Substituents to the silyl group include, for example, a halogen group, an unsaturated group,
Examples include carbonyl group, carboxyl group, nitrile group, thioether group, thioester group, alkyl group, and alkoxy group. Examples of the compound represented by the general formula (I) include those shown in Table 3 below.

The amount of the photosensitizer to be blended with the silicon-containing alkali-soluble resin is preferably 1 to 200 parts by weight per 100 parts by weight of the resin. The reason for this is that if the amount of the photosensitizer is less than 1 m part lff, it will not be possible to maintain sufficient solubility between the exposed and unexposed areas after exposure. This makes it difficult to prepare a resist solution, and the applicability to a substrate etc. may be impaired.

The silicon-containing resist according to the present invention includes, in addition to the silicon-containing alkali-soluble resin and photosensitizer, if necessary, an ultraviolet absorber, a surfactant, a sensitizer, and a thermal polymerization inhibitor for storage stability. Antihalation agents to prevent halation from the substrate, adhesion improvers to improve adhesion to the substrate, surfactants to smooth the surface of the coating film, or for modifying the coating film. other polymers,
For example, epoxy resin, polymethyl methacrylate resin,
It is also possible to blend propylene oxide-ethylene oxide copolymer, polystyrene, silicon substrate alone IJ 7-, etc.

The silicon-containing resist according to the present invention is dissolved in a solvent and applied onto a predetermined substrate directly or via a flattening layer. Examples of such solvents include ketone solvents such as cyclohexanone, acetone, methyl ethyl ketone, and methyl isobutyl ketone, cellosolve solvents such as methyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, and ester solvents such as ethyl acetate, butyl acetate, and isoamyl acetate. Alternatively, mixed solvents thereof can be used.

Next, a method of forming a pattern using a silicon-containing resist according to the present invention will be explained.

First, a polymer material layer (planarization layer) is formed on a substrate.

Examples of the substrate used here include a single silicon substrate doped with impurities, a semiconductor substrate in which a conductive film such as a polycrystalline silicon film is provided on the silicon substrate via a silicon oxide layer, and a blank mask. As the resin constituting the flattening layer, for example, any polymeric material that can be used to form a thin film can be used.17 Usually, 0FPl? as a novolac ultraviolet resist is used. -5000, 0
NPR-800H8 (all product names manufactured by Tokyo Ohka Co., Ltd.)
, HPR-204 (trade name manufactured by Hunt Co., Ltd.) or a photosensitive silicone resin. Such a flattening layer can be formed by applying a solution in which the resin is dissolved in a solvent onto the substrate using a spinner, for example, and drying the solution.

Suitable solvents used here include, for example, toluene, xylene, ethyl cellosolve acetate, and cyclohexanone. Furthermore, the solution may further contain additives such as diazide compounds for enhancing properties such as thermosetting properties. The viscosity of the solution is desirably adjusted to 20 to 100 cps%, more preferably 80 to 100 cps, considering application using a spinner or the like.

Furthermore, it is desirable that the thickness of the planarization layer is in the range of 1 to 2 μm, more preferably 1.5 to 260 μm. The reason for this is that if the thickness of the planarizing layer deviates from the above range, there is a risk that the resolution will decrease or that a substrate with steps may not be planarized. Note that the solution may be applied onto the substrate, dried, and then subjected to baking treatment.

The baking treatment conditions are a temperature sufficient to evaporate the solvent and a temperature exceeding the glass transition point of the constituent resin of the flattening layer used.
~120 minutes, preferably at 80~220°C for 1~90 minutes, and in the case of photosensitive silicone resin, usually 50 ~
0.5 to 120 minutes at 200°C, preferably 80 to 12
It may be carried out at 0°C for 1 to 60 minutes.

Next, on the flattening layer, the silicon-containing alkali-soluble resin and a photosensitizer selected from silicon-containing naphthoquinone diazide, silicon-containing azide, or a compound represented by the general formula (I) above are applied, and the solvent is applied to the flattening layer. A resist layer is formed by applying the dissolved silicon-containing resist using, for example, a spinner and drying it. The viscosity of the silicon-containing resist is preferably 10 to 8%, more preferably 10 to 100 cps%, considering application using a spinner or the like.
It is desirable to adjust it to 0 cps. Further, the thickness of the resist layer is 0.1 to 1.0 μm, more preferably 0.1 μm to 1.0 μm.
It is desirable that the thickness be in the range of 1 to 0.8 μm. The reason for this is that if the thickness of the resist layer deviates from the above range, oxygen plasma resistance may be reduced or resolution may be reduced. Note that a silicon-containing resist is applied on the flattening layer,
After drying, baking may be performed. At this time, if the solvent remains in the resist layer, scattering of the exposure light increases, resulting in a decrease in resolution.

The resist layer is then exposed to radiation (e.g. wavelength 385
ni 43G nm, 313 nm, 254 nm
, ultraviolet rays, electron beams, X-rays, etc.) is selectively irradiated to perform pattern exposure. In this pattern exposure, either a contact exposure method or a projection exposure method can be adopted. Subsequently, the exposed resist layer is developed with an alkaline aqueous solution to dissolve and remove exposed or unexposed portions to form an upper layer pattern. Examples of the monoalkali aqueous solution used here include organic alkali aqueous solutions such as tetromethylammonium hydroxide aqueous solution, and inorganic alkali aqueous solutions such as ammonium aqueous solution, sodium hydroxide aqueous solution, and potassium hydroxide aqueous solution. Further, as the developing means, for example, a dipping method, a spray method, etc. can be adopted.

Next, using the upper layer pattern as a mask, the lower planarization layer is dry etched using oxygen plasma (oxygen RI).
Do E). At this time, the upper layer flaps and the flattening layer is exposed from the pattern by 10 to 10 degrees.

It has the oxygen RIE resistance of mold. A suitable profile is obtained by etching all of the planarization layer exposed from the upper pattern using oxygen RIE.

Note that etching by oxygen RIE is usually performed using lX
10-' ~l x 10-' torr, 0.0
It may be carried out for 1 to 120 minutes under conditions of 1 to 1 OW/cd.

Next, the substrate is etched using the pattern formed by the above method as a mask. For etching, wet etching, dry etching, etc. are used.
Dry etching is preferred when forming a fine pattern of micrometers or less. In this etching,
The remaining resist pattern is removed using a stripping agent such as J-100 (trade name, manufactured by Nagase Kasei Co., Ltd.) or oxygen gas plasma.

(Function) The silicon-containing resist of the present invention is composed of an alkali-soluble resin containing silicon and a photosensitizer selected from silicon-containing naphthoquinone diazide, silicon-containing azide, or a compound represented by the above general formula (I). Therefore, it has extremely excellent oxygen RIE resistance and can exhibit a good masking effect against dry etching of the underlying planarization layer caused by oxygen plasma. Furthermore, since it contains an alkali-soluble resin containing silicon as one component, it also has good alkali developability. Furthermore, by adding a photosensitizer,
High sensitivity to ultraviolet rays, X-rays, and electron beams can be achieved. Therefore, it has excellent oxygen RIE resistance, is difficult to swell in the development process, and can achieve high resolution, and furthermore, by applying a two-layer lithography process, it becomes possible to form a fine two-layer pattern with a high aspect ratio.

(Example of the invention) Examples of the present invention will be described in detail below.

Examples 1 to 14 First, the silicon-containing alkali-soluble resin shown in Table 4 below and the photosensitizer shown in Table 5 below were blended in the proportions shown in Table 6 below, and the mixture was mixed with ethyl chloride. Seven silicon-containing resists with a concentration of 20% were prepared by dissolving with cellosolve acetate.

Next, a solution of novolak resist (product name: 0NPI?-800118, manufactured by Tokyo Ohka Co., Ltd.) was applied onto the silicon substrate, dried, and then heat-treated at 200° C. for 15 minutes to form a flattening layer with a thickness of 2.0 μm. Formed. Subsequently, each of the silicon-containing resists was applied on the flattening layer of the silicon substrate and dried to form a resist layer with a thickness of 0.6 μm. Exposure was carried out using the following conditions: NA was 0.35, and the exposure amount was as shown in Table 6. . Subsequently, each exposed resist layer was developed for 40 seconds with a tetramethylammonium hydroxide (TMAH) aqueous solution having the concentrations shown in Table 6 to form an upper layer pattern.

Next, each silicon substrate on which the upper layer pattern was formed was etched using a dry etching device (manufactured by Tokuyo Seisakusho Co., Ltd., trade name: I).
RRIB), and reactive ion etching (RIE) using oxygen plasma was performed under the conditions of 2×1O−2 torr and output of 0.013 W/d to transfer the upper layer pattern to the lower planarization layer.

Comparative Example 1.2 First, the silicon-containing alkali-soluble resin shown in Table 4 below and the photosensitizer shown in Table 5 below were blended in the proportions shown in Table 6 below, and the mixture was mixed with ethyl Two types of silicon-containing resists were prepared by dissolving with cellosolve acetate and having a concentration of 20%.

Next, a solution of novolak resist (product name: 0NPR-8001 (S) manufactured by Tokyo Ohka Co., Ltd.) was applied onto the silicon substrate, dried, and then heat-treated at 200° C. for 15 minutes to form a flattened layer with a thickness of 2.0 μm. Subsequently, each of the silicon-containing resists was applied on the planarization layer of the silicon substrate and dried to form a resist layer with a thickness of 0.8 μm. Exposure was carried out using ultraviolet rays with a wavelength of NA 0.35 and the exposure amount shown in Table 6.Subsequently, each resist layer after exposure was treated with tetramethylammonium at a concentration shown in Table 6. An upper layer pattern was formed by developing with a hydroxide (TMAH) aqueous solution for 40 seconds.After this, oxygen reactive ion etching was performed in the same manner as in Examples 1 to 14 to transfer the upper layer pattern to the lower flattening layer. did.

Therefore, regarding Examples 1 to 14 and Comparative Example 1.2, the oxygen RIE resistance of the upper layer pattern during RIE with oxygen plasma of the planarization layer using the upper layer pattern as a mask,
The resolution of the two-layer pattern after RIE of the planarization layer using oxygen plasma using the upper layer pattern as a mask was also investigated. The results are also listed in Table 6. The oxygen RIE resistance of the upper layer pattern was evaluated from the ratio of the etching degree to the planarization layer.

As is clear from Table 6 below, it can be seen that the silicon-containing resist of the present invention has excellent oxygen RIE resistance and can form a fine upper layer pattern by alkaline development. It is also found that by performing oxygen plasma RIE using the upper layer pattern as a mask, the pattern can be faithfully transferred to the planarization layer, and a fine and highly accurate two-layer pattern can be formed. On the other hand, the upper layer pattern made of the resist of Comparative Example 1 corresponding to Example 2 and Comparative Example 2 corresponding to Example 6 has excellent oxygen RIE resistance, but has a low resolution of 0.45 μm. Moreover, since the pattern profile in the width of the upper layer pattern is triangular, it is difficult to faithfully transfer the pattern to the flattening layer.

In addition, although the above embodiment describes an example in which the method is applied to a method for forming a two-layer pattern, the present invention can be similarly applied to the formation of a single-layer pattern.

[Effects of the Invention] As detailed above, the present invention provides excellent oxygen resistance to RIE.
It is possible to obtain a silicon-containing resist that has high sensitivity to radiation, can be developed with alkali, and can form highly accurate patterns with little swelling due to development. By applying this method, it is possible to easily form a fine two-layer pattern with a high aspect ratio, and it has remarkable effects such as being able to be effectively used in manufacturing fine and highly integrated semiconductor devices.

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Claims (1)

[Scope of Claims] It is characterized by comprising an alkali-soluble resin containing silicon and a photosensitizer selected from silicon-containing naphthoquine diazide, silicon-containing azide, or a compound represented by the following general formula (I). Silicon-containing resist. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) However, R_1 to R_4 in the above general formula (I) are hydrogen, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms,
It represents a substituted or unsubstituted aryl group or a substituted or unsubstituted silyl group.