JPS6017444A - Radiation sensitive resin composition - Google Patents

Abstract

PURPOSE:To obtain a radiation sensitive resin composition having superior radiation sensitivity and dry etching resistance and useful to manufacture a semiconductor element, etc. by using an aldehyde polymer contg. silicon and an alkali- soluble polymer as principal components. CONSTITUTION:The desired radiation sensitive resin composition is obtd. by using an aldehyde polymer contg. silicon (A) and an alkali-soluble polymer (B) as principal components. A copolymer of an aliphatic aldehyde monomer contg. one or more silicon atoms such as beta-trimethylsilylpropanal with an aliphatic aldehyde monomer contg. no silicon atom such as beta-phenylpropanal is suitable for use as the component A. Novolak resin, polyhydroxystyrene or the like is suitable for use as the component B. The components A, B are preferably contained in 5:95-80:20.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to electron beams, X-rays, ion beams, etc. The present invention relates to a radiation-sensitive resin paraboloid that is sensitive to radiation such as.

[Background of the invention]

Conventionally, methods using photoresists sensitive to ultraviolet rays or visible light have been widely used in pattern forming methods for manufacturing electronic components such as semiconductor devices, magnetic bubble memory devices, and integrated circuits.

In recent years, in order to increase the density and integration of semiconductor devices, there has been a demand for a method for forming patterns with a width of 1 μm or less. However, in the method using ultraviolet rays or visible rays as described in 1 above, it is extremely difficult to accurately form a pattern with a width of 1 μm or less due to the inherent properties of the light, such as diffraction, scattering, and interference. Since the yield is also significantly reduced, this method is not suitable for forming patterns with a width of 1 μm or less.

To deal with this, instead of the photorin graphini mentioned above,
Lithography techniques that use high-energy radiation such as electron beams, X-rays, and ion beams have been developed and researched, and various materials that are sensitive to the radiation have been studied. The radiation-sensitive resin composition that is the object of the present invention is also the above-mentioned resist. It is abbreviated as "Resist".

There are two types of electron beam resists: positive type, in which the irradiation of radiation induces the cutting action of polymer chains, and the irradiated area becomes soluble in the developing solution, forming a pattern; There is a negative-type resist in which the irradiated area becomes insoluble in the developing solution and forms a pattern.An example of a positive-type electron beam resist is

Examples include poly(methyl methacrylate), poly(1-butenesulpone), etc., but positive resists reflect incident light more than negative resists, similar to the case with tre resists.

It is an excellent microfabrication regime for producing high-resolution patterns because it can reduce pattern disturbances caused by scattering.

However, conventional positive electron beam resists, including those exemplified above, have a sensitivity that is 1/1 that of negative resists.
As a result, the time required for pattern formation is low, making it impractical in terms of productivity.Also, positive electron beam resists are less practical than negative resists.

It is inferior in dry etching resistance, and improvements have been desired.

[Purpose of the invention]

The purpose of the present invention is to eliminate the drawbacks of the prior art described above, and to provide a material that has high sensitivity to high-energy radiation such as electron beams, X-rays, and ion beams, and has excellent radiation sensitivity with excellent dry etching resistance. It is an object of the present invention to provide a resin composition, particularly a positive radiation-sensitive resin composition having the above-mentioned property that the irradiated portion becomes alkali-soluble upon radiation irradiation.

[Summary of the invention]

The radiation-sensitive resin composition according to the present invention is characterized in that it contains a silicon-containing aldehyde polymer and an alkali-soluble monomer as main components.

In aldehyde-based polymers having a polyneedle structure, polymer chains are chain-disintegrated by irradiation with high-energy radiation such as electron beams, X-rays, and ion beams, and are scattered simultaneously with the radiation.

Therefore, when radiation is irradiated to the radiation-sensitive resin composition of the present invention (=41+<, Mi, hereinafter referred to as a child beam resist), only the alkali IJ Tl1J soluble polymer is present in the irradiated area. will remain,
By carrying out alkaline development, only the irradiated portions are selectively dissolved and a positive resist pattern can be obtained.

In general, homopolymers of aliphatic aldehydes have high crystallinity and are poorly soluble in many organic solvents, so they cannot be used as resist materials.

It is known that an aldehyde copolymer with improved solubility can be obtained by subjecting a mixture of two or more aliphatic aldehydes to anionic formation. It has been found that this aldehyde copolymer can be used as an electron beam resist (e.g., Tanaka et al., Kouka, 20.694.1).
963). However, 5 common aliphatic aldehyde copolymers that are compatible with alkali-soluble polymers cannot be obtained.

What is important about electron beam resists that have aldehyde polymers as their main component is that (1) the aldehyde polymers are easily decomposed and gasified by radiation irradiation, and (2)
Good compatibility between the aldehyde polymer and the alkali-soluble polymer, 02 points.

As a result of various studies, the present inventors have found that aldehyde polymers obtained by polymerizing aliphatic aldehydes containing silicon atoms have excellent solubility in organic solvents, excellent compatibility with alkali-soluble polymers, and , and is highly sensitive to radiation.

It was discovered that it is excellent as a resist material.

In other words, the inclusion of silicon atoms in the aldehyde polymer increases radiation absorption properties such as electron beams and It has significantly improved properties and is compatible with alkali-soluble polymers. In addition, in the electron beam resist of the present invention, in an unirradiated state.

The aldehyde polymer prevents the alkali-soluble polymer from being dissolved by alkali, and the aldehyde polymer scatters when irradiated with radiation.

The irradiated area becomes alkali-soluble.

Next, the silicone-containing aldehyde polymer, which is one of the main components of the composition of the present invention, will be described.

This silicon-containing aldehyde-based polymer is usually used as a copolymer from the viewpoint of compatibility with an alkali-soluble polymer. That is, the silicon-containing aldehyde polymer is an aliphatic aldehyde monomer containing at least one silicon atom.

Aliphatic aldehyde monomers that do not contain silicon atoms,
It is obtained by copolymerization by anionic polymerization.

The aliphatic aldehyde monomer has general formula 1? C
, IIO, and R contains a silicon atom. Alternatively, aliphatic aldehydes which are an alkyl group, a halogenated alkyl group, an aralkyl group, or a halogenated aralkyl group that do not contain I2 can be mentioned. The number of carbon atoms in the alkyl group in the above alkyl group, halogenated alkyl group, aralkyl group, and halogenated aralkyl group is preferably 1 to 8.

The polymerization catalyst used when obtaining the silicon-containing aldehyde polymer, which is one of the main components of the composition of the present invention, by anionic polymerization includes dimethylaluminum(diphenyl)amide (C115)2-At-N(C6H5)2, diethyl Aluminum (sif-nyl)amide (C2H5) 2 A
L N (C6115) 2. Ethylaluminum bis(sif-nyl)ami)' (C2H3) -At CM
(C6ns)2)2-ethylzinc(diphenyl)
Amide (C2H5) -Zn -N (C6H5)2.
:cf magnesium (diphenyl)amide (C2”
5) My #((:'6ils)2), but is not limited thereto.

Although there is no limit to the amount of the catalyst, it is appropriate to add the catalyst in a proportion of 0.1 to 5 moles relative to the aldehyde monomer mixture.

When performing anionic polymerization, it is not necessary to use one polymerization medium, but if necessary, it is preferable to use a hydrocarbon such as toluene or an ethyl ether solvent.

The 1M reaction can be carried out at a temperature in the range of 100°C to -100°C, but a temperature of 150°C to -80°C is usually suitable.

Further, as for the atmosphere for polymerization No. 11, it is preferable to sufficiently replace the air in the vessel with an inert gas such as nitrogen.

Note that the method for polymerizing the silicone-containing aldehyde polymer, which is one of the main components of the composition of the present invention, is not limited to the above. There is no problem in adopting any method such as charging the catalyst itself or adding the catalyst itself or its solution to the aldehyde monomer itself or its solution.

Next, the alkali-soluble polymer, which is another product of the composition of the present invention, will be described. Examples of the alkali-soluble polymers include novolak resins (here, meaning condensation polymers of formaldehyde, carbolic acid, cresol, and other alkylphenols), polyhydroxystyrene resins, and the like. Novolank resins can be used in the form of homocondensation polymers or cocondensates, and polyhydroxystyrene resins can also be used in the form of homopolymers or copolymers. (below,
Novolak resin, polyhydroxystyrene resin).

These may be used alone or in the form of a mixture of the two.

Novolac resins and polyhydroxystyrene resins are commercially available. For example, the novolak resin includes a monocarboxylic acid novolac resin, a cresol novolak resin, a monocarboxylic acid/cresol novolak resin, and the like. Examples of the polyhydroxystyrene resin include polyvarabinyltunol resin, brominated polyvarvinylfunol resin, and the like. The molecular weight, cocondensation composition ratio, and copolymerization composition ratio of these alkali-soluble polymers can be arbitrarily changed depending on the purpose. When used as a resist material.

Considering the film formability, heat resistance, etc. of the resist film, it is desirable that the number average molecular weight is 500 to io, oooQ.

The blending ratio of the silicon-containing aldehyde-based polymer and the alkali-soluble polymer, which are the main components of the composition of the present invention, is 99 to 1 part by weight of the alkali-soluble polymer to 1 to 99 parts by weight of the silicon-containing aldehyde-based polymer. It is preferable to use it within the range of .

More preferably, the proportion of the alkali-soluble polymer is 95 to 2 to 5 to 80 bases of the silicon-containing aldehyde polymer.
It is desirable to use it within the range of 0-layer seams. When a composition outside the above range is used, resist properties such as radiation sensitivity and dry etching resistance often deteriorate significantly, making it difficult to put it into practical use.

Next, a method of using the composition of the present invention to form a pattern of a semiconductor device or the like will be explained. - To give an example, the composition of the present invention dissolved in an organic solvent such as cyclohexanone is used, and is usually applied to an element substrate by a spin coating method or a dip coating method.

After coating and pre-baking under appropriate temperature conditions, 2. When the desired pattern is irradiated with radiation, the silicone aldehyde-containing polymer in the irradiated area breaks down in a chain manner and scatters.
In the irradiated area, only the alkali-soluble polymer remains, and in the unirradiated area, the silicone aldehyde-containing polymer still prohibits the alkali-soluble polymer from being dissolved by alkali, so the difference between the irradiated area and the unirradiated area is In between, there is a developer (
According to 1, there is a difference in solubility in alkaline solutions), and pattern formation is possible.

Examples of alkaline solutions for the developer include aqueous solutions of tetraalkylammonium hydroxides such as tetramethylammonium hydroxide, and aqueous solutions of inorganic alkalis such as hexasodium phosphate and sodium hydroxide. , an alkaline solution is sufficient.

It is not limited to the above-mentioned examples.

Development can be carried out by methods such as immersion and spray development. Furthermore, in order to obtain a resist pattern with a small amount of radiation irradiation, it is effective to perform heat treatment at a temperature of about 100 V after radiation irradiation and before development.

[Embodiments of the invention]

Examples of the method for synthesizing the silicon-containing aldehyde-based polymer, which is the main component of the composition of the present invention, and the method for synthesizing the catalyst and monourine therefor, as well as examples of the preparation and use of the composition of the present invention are given below. will be explained step by step.

Example 1 (Diethylaluminum (diphenyl)amide as a polymerization catalyst for a silicon-containing aldehyde polymer.

(C2115)2 At-N (C6t15)2 At
-N (cJ15)2 synthesis method. ) Stirrer, #J lower funnel, three-way cock, and thermometer (=t) After purging the inside of a 200-meter four-bottle flask with nitrogen, 55 ml of toluene, (C1l, C'112), At 1
4.5 f (0,127 mat)'& under a nitrogen stream, introduce using a syringe through a three-way stopcock.

After stirring for a while to make a homogeneous solution, 21.4 f of diphenylamine (27 mOL of OA) was added to 1-
A solution of 40 g of luene is gradually added dropwise.

After the dropwise addition was completed, the temperature of the reactant was raised to 60°C, and the temperature was continued for 2 hours.
The reaction was completed by stirring slowly for a while.

The produced diethylaluminum (diphenyl)amide,
(C2H3)2At-N(CJI)2 was stored as a toluene solution in a container with a three-way cock under a nitrogen stream.

Example 2 (Synthesis method of β-trimethylsilylpropanal as an example of silicon-containing arte monomer.) Tetrahydrofuran was added to a 500 ml four-bottle flask equipped with a stirrer, a dropping funnel, a thermometer, and a condenser tube. 300rn1. , finely crushed lithium 3.045' (0.44 mOL)
, and trimethylsilyl chloride 54.25 f (
0.5 mOL) was added dropwise over about 1 hour while keeping the liquid temperature at 0 υ, and then stirring was continued at room temperature for 15 hours.

After the reaction, lithium and lithium chloride were separated, tetrahydrofuran and excess trimethylsilyl chloride were distilled off, and then distilled under reduced pressure (C'n, ), 5tcl.
l, cn = ctrost (cu, ), (boiling point 11ooV30 mm llq)
This was left in hydrochloric acid-acetone at room temperature for 1 hour to be hydrolyzed, and then transferred to a heated section under reduced pressure.
I got it.

Examples 6 to 4 (Synthesis method of silicon-containing aldehyde polymer.) Polymerization was carried out by
This was carried out using a polymerization tube with a three-way cock. That is, about 100
- in a cylindrical polymerization vessel with a capacity of - under nitrogen flow.
A silicon-containing aldehyde monomer and a silicon-free aldehyde monomer in the proportions shown in the table and Tk:L:/'I as a solvent were introduced using a syringe through a three-way stopcock.

The above container containing the monomer solution was cooled to 0υ in an ice-water bath, and while the container was being moved vigorously, the catalyst (C2H3)2 AI-N (C6Hs)2 obtained in Example 1 was added to the container at a rate of 1 to 5 omot of monomer. Drop it gradually so that it becomes a mob.

After adding the catalyst, the vessel is cooled to -78'C in a dry ice/acetone bath and left undisturbed for 24 hours to allow polymerization. After Polymerization 1. The polymerization mixture was treated with ammoniacal methanol to decompose the catalyst, then immersed in methanol for 1 day, filtered, washed several times with methanol, and dried in vacuum.

Note that, depending on the case, this may be the opposite of the above embodiment.

The catalyst solution may be introduced into the polymerization container first, and the monomer solution may be added thereto to carry out the polymerization.

Table 1 shows copolymers of various compositions synthesized in this way. The composition ratio of the copolymer was determined by cumulative analysis. In addition, the monomer abbreviations in Table 1 are TMSPA, Ph1
) A and BA represent β-trimethylsilylpropanal, β-phenylpropanal and butanal, respectively.

Table 1 Example 5 (For the preparation and use of the composition of the invention) Example 3
copolymer 2 of β-trimethylsilylpropanal and β-phenylpropanal, f (amount 6B,
Poly p-vinyltunol resin (molecular weight approx. 4000)
8 parts by weight were dissolved in cyclohexanone to give 1% by weight.
A resist solution was prepared.

Subsequently, the resist n solution described in "2" was applied onto a silicon wafer and prebaked at 80 υ for 20 minutes to form a 15 μm thick polymer film. This was placed in an electron beam irradiation device, and irradiation was performed with an electron beam of 8E20 KV accelerated in vacuum at different doses.

Thereafter, it was developed for about 30 seconds with a 1 weight aqueous solution of tetramethylammonium hydroxide and washed with water. For areas irradiated with various irradiation doses, the remaining polymer film thickness was measured using a thin film step needle, and the remaining film thickness (normalized) was plotted against the electron beam irradiation dose (coulombs/-). , an irradiation characteristic curve showing the electron beam sensitive characteristics was obtained.

From this, we determined the minimum irradiation dose at which the residual film rate would be zero, and found that it was 2.
It was confirmed that the resistance was X10""'coulombs/-, and that it was an extremely sensitive positive resist. For example, the electron a sensitivity of polymethyl methacrylate, which is a typical positive resist, is I x 10 = coulomb/cr/l, and the positive resist material of this embodiment of the present invention has a It was confirmed that the sensitivity was approximately two orders of magnitude higher.

Next, we investigated the resistance to argon ion milling, and found that the film reduction rate of this resist material was 20 OA' under ion milling conditions of 600 V, 0.5 A, and a gas pressure of 2, OX 10-"Jforr. /
It was min.

On the other hand, the film reduction rate of polymethyl methacrylate, which is a typical positive resist, was 500.4/mcn, and it was confirmed that this resist material exhibits high resistance to dry etching.

Examples 6 to 11 (Regarding the preparation and use of the compositions of the present invention) The copolymers of β-trimethylsilylpropanal obtained in Examples 6 and 4 and the alkali-soluble polymers were mixed at the weights shown in Table 2. About 1 liter of a resist solution according to the present invention was prepared by dissolving in cyclohexane in the following proportions. Apply this on a silicon wafer and heat it at 80tX for 20 minutes to approximately 2μ
A polymer film with a thickness of m was formed.

Then, acceleration voltage 20KV o) Electron beam or 1o13V
soft X-rays (Motα) were irradiated, and the electron beam sensitivity or soft X-ray sensitivity was measured in the same manner as in Example 5. At the same time, we also investigated resistance to argon ion milling. These results are summarized in Table 2.

As is clear from Table 2, the resist materials according to all examples have high sensitivity to radiation and high resistance to dry etching.

Comparative Example Similar to Examples 4 to 11, an attempt was made to mix a copolymer of butyraldehyde and acetaldehyde with an alkali-soluble polymer, but a solvent that could dissolve both was not found and it could not be put to practical use. .

〔Effect of the invention〕

The radiation-sensitive resin composition according to the present invention is constructed and used as described above, and exhibits excellent properties. That is, it is highly sensitive to radiation such as electron beams, X-rays, and ion beams, and has excellent resistance to dry etching. Furthermore, in the composition according to the present invention, the irradiated portion becomes alkali-soluble upon irradiation and forms a positive pattern, so it has excellent performance as a positive electron beam resist that forms a pattern with high resolution.

Therefore, one composition according to the present invention is suitable for use in semiconductor devices.

It can be used to form patterns for manufacturing electronic components such as magnetic bubble memory elements and integrated circuits, with remarkable effects.

Claims (1)

[Scope of Claims] 1. A radiation-sensitive resin composition comprising a silicone aldehyde-based polymer and an alkali-soluble polymer as main components. 2. Claims in which the silicon-containing aldehyde polymer is a copolymer of an aliphatic aldehyde monomer containing at least 7 silicon atoms and an aliphatic aldehyde monomer containing no silicon atoms. The radiation-sensitive resin composition of item 1. 6 The aliphatic aldehyde monomer is generally represented by 2R-〇HO, and R contains a silicon atom. The radiation-sensitive resin composition according to claim 2, which is an alkyl group, a halogenated alkyl group, an aralkyl group, or a halokea chemical 7 #alkyl group. 4. The alkyl group and halogenated alkyl group. Claims @3 in which the alkyl in the aralkyl group and the halogenated aralkyl group has 1 to 8 carbon atoms.
2. Radiation-sensitive resin composition. 5. The radiation-sensitive resin composition according to claim 1, wherein the alkali-soluble polymer is a novolak resin, polyhydroxystyrene ml, or a mixture of both. 66. The radiation-sensitive resin composition according to claim 1, wherein the content ratio of the silicon-containing aldehyde polymer and the alkali-soluble polymer is 1:99 to 99:1, preferably 5:95 to 80:20. . Z. The radiation-sensitive resin composition according to claim 4, wherein the silicon-containing aldehyde-based polymer is a copolymer of β-trimethylsilylpropanal and an aliphatic aldehyde monomer.