JPH08305028A - Resist - Google Patents

Abstract

PURPOSE: To obtain a resist having photosensitivity, excellent in dry etching resistance and capable of forming a high precision pattern having satisfactory thermal stability. CONSTITUTION: This resist is made chiefly of polysilane having repeating units represented by general formula I or II.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist capable of forming a negative pattern.

[0002]

2. Description of the Related Art In the field of electronic parts, such as semiconductor integrated circuits, which require various fine processing, pattern formation using a resist has been widely performed so far. As such a pattern forming method, conventionally, for example, a so-called single-layer resist method in which only one resist film is formed on a wafer has been generally used. However, in the manufacture of semiconductor integrated circuits, the minimum processing dimension has been reduced year by year, and various problems have been pointed out regarding this single-layer resist method.

That is, in the semiconductor integrated circuit, the vertical dimension is not so much reduced as compared with the horizontal dimension, so that the ratio of the height to the width of the resist pattern has to be large. Therefore, it has become more difficult to suppress the dimensional change of the resist pattern on the wafer having a complicated step structure as the pattern becomes finer.

Further, in various exposure methods, another problem has arisen with the reduction of the minimum size. For example, in light exposure, the interference effect of reflected light due to the step on the semiconductor substrate has a great influence on the dimensional accuracy. on the other hand,
In the electron beam exposure, there is a problem that the height-to-width ratio of a fine resist pattern cannot be increased due to the proximity effect caused by electron backscattering.

A multi-layer resist system has been developed as a method for solving the above problems. For more information on this multilayer resist system, see Solid State Technology, 74 (1981) [Solid State Technology 74
(1981)], but many other researches on multilayer resist systems have been published. Currently, the most commonly attempted method is a resist system having a three-layer structure, in which a bottom layer having a role of planarizing a semiconductor substrate and preventing reflection from the substrate and a mask for etching the bottom layer are used. And an uppermost layer as a photosensitive layer.

However, although the above three-layer resist system has an advantage that fine patterning can be performed as compared with the single-layer resist method, it has a problem that the number of steps until pattern formation is increased. That is, there is no resist that satisfies both the photosensitivity to energy rays such as deepUV and the resistance to reactive ion etching by oxygen plasma (oxygen RIE resistance), so these functions are provided in different layers. As a result, the number of steps has been increased.

[0007]

As described above, in the conventional multi-layer resist system, there is no resist satisfying both photosensitivity and oxygen RIE resistance, so that it is necessary to separately form layers having these functions. Therefore, there is a problem that the number of steps up to pattern formation increases.

An object of the present invention is to solve such problems and to provide a resist which has photosensitivity, excellent dry etching resistance, and good thermal stability and which enables highly precise pattern formation. .

[0009]

The present invention, which has been made to achieve the above object, is a resist comprising a polysilane having a repeating unit represented by any one of the following general formulas (1) and (2). is there. That is, the resist of the present invention is characterized by comprising polysilane in which a hydroxyl group, an alkoxy group or an acetoxy group directly bonded to Si of the main chain is introduced into a side chain.

[0010]

Embedded image

In the resist of the present invention, the Si—Si main chain of polysilane as described above is decomposed by irradiation with energy rays such as light, electron beams, X-rays, etc. By taking in oxygen and water, a Si-OH bond is generated. On the other hand, when an alkoxyl group or an acetoxy group is introduced into the side chain of polysilane, these are converted into hydroxyl groups by irradiation with energy rays, and Si-OH bonds are generated also here. Further, since such silanol hydroxyl groups immediately react with each other, as a result, in the exposed portion, a glass matrix is formed in which silicon atoms are three-dimensionally cross-linked by the Si—O—Si bond and cured. Therefore, there is a difference in solubility with respect to the developing solution between the unexposed portion made of polysilane having a one-dimensional polymer structure, and the unexposed portion is selectively dissolved and removed by the developing solution to obtain a negative pattern. Moreover, the pattern obtained here is S
Since the glass matrix composed of i-O-Si bonds is the main component, the resist of the present invention can exhibit thermal stability comparable to that of an inorganic resist, that is, extremely excellent heat resistance and dimensional stability.

In the present invention, the polysilane as described above may be a homopolymer or a copolymer, and further, a copolymer with a repeating unit other than the repeating unit represented by the general formula (1) or (2). May be The molecular weight of the polysilane is not particularly limited, but the degree of polymerization is 5 to 50,000, more preferably 20 to 10,
00 is preferable. The reason for this is that if the degree of polymerization of polysilane is too low, it becomes difficult to form a coating film having sufficient durability, and conversely, if the degree of polymerization of polysilane is too high, the solubility in organic solvents decreases. Here, specific examples of the polysilane that can be used in the present invention will be shown.

[0013]

Embedded image

[0014]

[Chemical 4]

[0015]

Embedded image

[0016]

[Chemical 6]

[0017]

[Chemical 7]

[0018]

Embedded image

The above-mentioned polysilane can be synthesized by the following method. (A) For example, by reacting dichlorosilane represented by the following general formula (S1) or (S2) with sodium metal, lithium metal or the like in an organic solvent such as toluene or ether, and desalting and condensing the dichlorosilane. Can be synthesized. (B) In addition, K. Matyzazeski et al., J. Am. Organ
omet. Chem. , 340, 1988, 7, poly (diarylsilane) s represented by the following general formulas (PS1) to (PS5) are treated with an acid such as trifluoromethanesulfonic acid in an organic solvent such as methylene chloride. It can also be synthesized by reacting with an alcohol having a desired substituent site after the reaction. At this time, a polysilane having an acetoxy group introduced into its side chain can be synthesized by reacting a carboxylic acid or a carboxylic acid salt instead of the alcohol.

[0020]

[Chemical 9]

In addition to these methods, the polysilane having an alkoxyl group on one side chain is (c) K.K. Matyjaz
ewski, Macromol. Chem. Macro
mol. Symp. , 42/43, 269-280, 1
As reported in 991, a method of ring-opening polymerization of a four-membered ring of Si substituted with an alkoxyl group, (d) a method of electrolytic polymerization using a halide of a silicon atom substituted with an alkoxyl group, (E) Kaeda et al., Chem. L
ett. , 835, 1994,
A method of polymerizing an alkoxy compound of a silicon atom by a disproportionation reaction using a catalyst such as a base, (f) Yu-Lin
g Hsiao et al. Am. Chem. Soc. , 1
Si-H, such as poly (phenylhydrosilylene), as reported in 994, 116, 9779-9780.
It can also be synthesized by a method of reacting a resin having a bond with a carbonyl compound such as an aldehyde or a ketone under the action of AIBN (azobisisobutyronitrile).

Further, in the present invention, a chemically amplified resist can be obtained by blending a compound capable of generating an acid or a base upon irradiation with light with the above-mentioned polysilane. That is, in this case, in the coexistence of an acid or a base generated by light irradiation, photolysis of the Si-Si main chain of polysilane, formation of Si-OH bond, and mutual reaction of silanol-containing hydroxyl groups are promoted. It is possible to form a pattern with a higher degree of accuracy than that used in the above.

Examples of the compound capable of generating an acid upon irradiation with light include sulfonium salts, iodonium salts, nitrobenzyl compounds and naphthoquinonediazide-4-sulfonic acid esters. Of these, the sulfonium salt is a particularly preferable component.
Specific examples of compounds that can be used in the present invention to generate an acid or a base upon irradiation with light are shown below.

[0024]

[Chemical 10]

[0025]

[Chemical 11]

[0026]

[Chemical 12]

[0027]

[Chemical 13]

The chemically amplified resist as described above is
It can be prepared by dissolving polysilane and a compound capable of generating an acid or a base upon irradiation with light in a suitable organic solvent. Specific examples of the organic solvent here include toluene, xylene, dimethylformamide, dimethylacetamide, methyl cellosolve, o-dichlorobenzene, chloroform, ethanol, i-propyl alcohol, cyclopentanone, cyclohexanone, ethyl cellosolve acetate, and acetone. , Methyl ethyl ketone, ethyl acetate, butyl acetate, etc. are exemplified, and these can be used alone or in the form of a mixture. Further, at this time, it is preferable to add 0.01 to 30% by weight, more preferably 0.5 to 5% by weight, of a compound capable of generating an acid or a base upon irradiation with light, to the polysilane. If it is less than 0.01% by weight, the acceleration of the reaction in the exposed area due to the addition of a compound that generates an acid or a base upon irradiation with light is small,
On the other hand, if it exceeds 30% by weight, the storage stability of the resist tends to decrease.

To specifically form a desired pattern with the resist of the present invention, first, the resist solution as described above is applied onto a predetermined substrate. Next, by prebaking the obtained coating film, the organic solvent is evaporated to some extent to form a resist film. Then, the surface of the resist film is irradiated with energy rays such as Deep UV light, KrF excimer laser light, electron beam, and X-ray through a desired mask pattern. The dose of energy rays at this time is Dee.
In the case of p UV light, 1 mJ / cm ^{2 to} 10 J / cm ² ,
In the case of an electron beam, it may be about 1 to 100 μC / cm ² , and either contact exposure or projection exposure may be used.

Here, the polysilane in the exposed area forms a glass matrix which is three-dimensionally crosslinked and hardened by Si—O—Si bonds based on the photoreactivity as described above. However, in some cases, after the light irradiation, the resist film may be hard-baked at about 90 to 130 ° C. to accelerate the reaction of polysilane in the exposed portion. Subsequently, development and cleaning are performed using an organic solvent such as alcohol as a developing solution. As the developing method here, a dipping method, a spray method or the like can be adopted. In this way, the polysilane in the unexposed area is dissolved and removed in the developing solution, while the exposed area insolubilized in the developing solution by forming the glass matrix remains as described above, and the negative pattern is accurately formed.

Next, the case of applying such pattern formation to a multi-layer resist system will be described more specifically. First, after applying a flattening agent on the substrate, usually 5
0 to 250 ° C, preferably 0.5 to 12 at 80 to 220 ° C
It is dried for 0 minutes, preferably for 1 to 90 minutes to form a flattening layer having a desired thickness. Examples of the substrate used here include a silicon wafer, a silicon wafer having various insulating films, electrodes, wirings and the like formed on the surface thereof and having a step, a blank mask, and the like. Any leveling agent may be used as long as it has such a purity that it does not cause any trouble in the production of semiconductor integrated circuits and the like. Examples of such a leveling agent include positive resists composed of substituted naphthoquinonediazide and novolac resin, polystyrene, polymethylmethacrylate, polyvinylphenol, novolac resin, polyester, polyvinyl alcohol, polyethylene, polypropylene, polyimide, polybutadiene, polyvinyl acetate. And polyvinyl butyral. These resins are used alone or in the form of a mixture.

Then, after applying a resist solution on the obtained flattening layer, the temperature is 50 to 200 ° C., preferably 80 to 120.
Prebaking is performed at 0.5 ° C. for 0.5 to 120 minutes, preferably 1 to 60 minutes to form a resist film having a desired thickness. As a method for applying the resist solution here, a spin coating method using a spinner, a dipping method, a jetting method, a printing method, or the like can be adopted. The thickness of the resist film can be arbitrarily adjusted by the coating method, the polysilane concentration in the resist solution, the viscosity, and the like.

Then, the resist film is exposed and developed as described above to form a negative pattern,
If necessary, heat treatment is performed at 50 to 120 ° C. for about 0.5 to 120 minutes. Next, the exposed flattening layer is etched using oxygen gas plasma or a suitable solvent using the formed pattern as a mask. At this time, an oxygen reactive ion etching method (oxygen RIE method) using oxygen gas plasma is more preferable, and is usually 1 × 10 ⁻⁴ to 1
× 10 ^-1 Torr, 0.01 to 10 W / cm ² to 1 to 120
Process for minutes. Here, the pattern formed using the resist of the present invention is exposed to oxygen RIE,
A silicon dioxide (SiO ₂ ) film or a film similar thereto is formed on the surface layer, and has a resistance to oxygen RIE that is 10 to 100 times that of the exposed planarization layer. Therefore, the flattening layer portion exposed from the pattern is selectively removed by the oxygen RIE method, and the optimum pattern profile is obtained.

Finally, the substrate is etched by using the pattern thus obtained as a mask. As an etching method at this time, for example, a wet etching method or a dry etching method is adopted, but when forming a fine pattern of 3 μm or less, the dry etching method is preferable. As the wet etching agent, an aqueous solution of hydrofluoric acid, an aqueous solution of ammonium fluoride, etc. when the silicon oxide film is an etching target, an aqueous solution of phosphoric acid, an aqueous acetic acid solution, an aqueous nitric acid solution, etc. when the aluminum is an etching target, When the chromium-based film is the etching target, an aqueous solution of cerium ammonium nitrate or the like is used.
As the dry etching gas, CF ₄ , C ₂ F ₆ ,
CCl ₄ , BCl ₃ , Cl ₂ , HCl, H _{2 and the} like can be mentioned. These gases are used in combination as required. As the etching conditions, the concentration of the wet etching agent in the reaction tank, the concentration of the dry etching gas, the reaction temperature, and the reaction time are based on the combination of the type of material used to form the fine pattern and the resist used. Etc., but the method is not particularly limited.

After the etching as described above, a pattern formed by using the flattening layer remaining on the substrate and the resist of the present invention is used as a pattern, for example, manufactured by Nagase Kasei Co., Ltd .: trade name: J-1.
00 or other release agent, oxygen gas plasma, etc. to remove.

It should be noted that, in addition to the above steps, there may be no problem in adding more steps depending on the purpose. For example,
For the purpose of improving the adhesion between the resist film and the flattening layer or the flattening layer and the substrate made of the resist of the present invention, for the purpose of removing the developing solution after developing the resist film after the pretreatment step performed before coating each solution. Examples include a rinsing step to be performed and an ultraviolet ray re-irradiation step to be performed before dry etching. Further, although the case where the resist of the present invention is applied to the multilayer resist system has been described above, the resist of the present invention can also be applied to a conventional single layer resist.

Further, in the resist of the present invention, a thermal polymerization inhibitor for increasing storage stability, an antihalation agent for preventing halation from the substrate, and an adhesive property for improving the adhesion to the substrate are added if necessary. Adhesion improver,
Additives such as ultraviolet absorbers, surfactants and sensitizers, and alkali-soluble resins may be blended.

[0038]

EXAMPLES First, according to the formulation shown in Table 1 below, polysilane and a compound capable of generating an acid or a base upon irradiation with light were dissolved in toluene, and sample No. Resists of Examples 1 to 12 and Comparative Examples were prepared. Here, the chemical formulas of the compounds represented by the abbreviations in Table 1 are specifically shown.

[0039]

Embedded image

[0040]

[Chemical 15]

[0041]

Embedded image

Next, these sample Nos. With respect to the resists 1 to 12, the resist film was formed on the substrate under the conditions shown in Table 1, exposure, hard baking, and development were sequentially performed to form a pattern. Table 1 also shows the sensitivity, resolution, and pattern shape of each sample at this time. As shown in Table 1, the sample No. In each of the resists of Examples 1 to 8, it is possible to accurately form a pattern having excellent resolution, and in particular, Sample No. 1 containing a compound capable of generating an acid or a base upon irradiation with light is used. In 1 to 6, extremely good pattern shapes were obtained.

[0043]

[Table 1]

Further, polysilanes A, B, as described above,
For E, a resist film was dissolved on toluene and a resist film was similarly formed on the substrate. Then, for polysilanes A and B, the entire surface was exposed, and then the temperature rising rate was set to 5 ° C. in an oxygen atmosphere.
Heat from room temperature to 500 ° C for thermogravimetric analysis (T
Weight loss was measured according to G). As a result, the weight reductions of polysilane A and B were 5% and 3%, respectively, whereas the weight reduction of polysilane E was remarkably large at about 40%, and in the pattern formed using the resist of the present invention, It was confirmed that the heat resistance and dimensional stability were also very excellent.

[0045]

As described in detail above, the resist of the present invention has photosensitivity and excellent dry etching resistance, and enables highly precise pattern formation with good thermal stability. There is great value.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jiulian Kou No. 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Within the Corporate Research and Development Center, Toshiba Corporation (72) Shuji Hayase, Komukai-Toshiba, Saiwai-ku, Kawasaki-shi, Kanagawa Town No. 1 Toshiba Corporation Research & Development Center

Claims (2)

[Claims] 1. A resist comprising a polysilane having a repeating unit represented by any one of the following general formulas (1) and (2). Embedded image 2. The resist according to claim 1, further comprising a compound capable of generating either an acid or a base upon irradiation with light.