JPH0158496B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention is sensitive to radiation such as electron beams, X-rays, and ion beams used for forming fine patterns necessary for manufacturing semiconductor devices, magnetic bubble memory devices, integrated circuits, etc. The present invention relates to a radiation-sensitive resin composition. [Background of the Invention] Conventionally, methods using photoresists sensitive to ultraviolet 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. has been done. 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, due to the inherent properties of the light such as diffraction, scattering, and interference,
It is extremely difficult to accurately form a pattern with a width of 1 μm or less, and at the same time, the yield is significantly reduced, so this method is not suitable for forming a pattern with a width of 1 μm or less. In order to deal with this, lithography techniques using high-energy radiation such as electron beams, Various materials exhibiting sensitivity have been studied. The radiation-sensitive resin composition targeted by the present invention is also the above-mentioned material, and hereinafter, the radiation-sensitive resin composition is
Generally, it is abbreviated as "electron beam resist" to distinguish it from conventional photoresist. There are two types of electron beam resists: positive type, in which irradiation with radiation induces polymer chain scission, and the irradiated area becomes soluble in developer, forming a pattern; There is a negative type that induces a crosslinking reaction and the irradiated area becomes insoluble in the developer, forming a pattern. Examples of positive electron beam resists include poly(methyl methacrylate), poly(1-butenesulfone), etc.; however, in almost the same way as photoresists, positive resists are It is excellent as a resist for microfabrication to generate high-resolution patterns because it can reduce pattern disturbance caused by reflection and scattering of incident light. However, conventional positive electron beam resists, including those exemplified above, have a sensitivity that is 1/10 to 1/1000 lower than that of negative resists, and as a result, the time required for pattern formation is longer. It was impractical in terms of productivity. Furthermore, positive type electron beam resists are inferior to negative type resists in terms of dry etching resistance, and improvements in this property have been desired. [Object of the Invention] The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to provide a material that has high sensitivity to high-energy radiation such as electron beams, X-rays, and ion beams, and has excellent dry etching resistance. It is an object of the present invention to provide a radiation-sensitive 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 by containing a silicone-containing aldehyde polymer and an alkali-soluble polymer as main components. When an aldehyde polymer having a polyether structure is irradiated with high-energy radiation such as an electron beam, an X-ray, or an ion beam, the polymer chains are broken down in a chain manner, and the polymer chains are scattered at the same time as the radiation is irradiated. Therefore,
The radiation-sensitive resin composition of the present invention (as described above,
It is abbreviated as electron beam resist. When radiation is irradiated to the irradiated area, only the alkali-soluble polymer remains in the irradiated area, and by performing alkaline development, only the irradiated area is selectively dissolved, forming a positive resist pattern. is 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 aldehyde copolymers with improved solubility can be obtained by anionically polymerizing mixtures of two or more aliphatic aldehydes. It has been found that this aldehyde copolymer can be used as an electron beam resist (eg Tanaka et al., Kouka, 20, 694, 1963). However, ordinary aliphatic aldehyde copolymers that are compatible with alkali-soluble polymers cannot be obtained. What is important about electron beam resists containing aldehyde polymers as their main component is that (1) the aldehyde polymers are easily decomposed and gasified by radiation irradiation, and (2) the aldehyde polymers and alkali solubility Two points are that it has good compatibility with the polymer. 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 It was discovered that it has high radiation sensitivity and 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 the unirradiated state, the aldehyde polymer inhibits the alkali-soluble polymer from being dissolved by an alkali, and upon irradiation, the aldehyde polymer scatters and is covered. The irradiated area becomes alkali-soluble. Next, it is one of the main components of the composition of the present invention.
A silicon-containing aldehyde polymer 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 obtained by copolymerizing an aliphatic aldehyde monomer containing at least one silicon atom and an aliphatic aldehyde monomer containing no silicon atom by anionic polymerization. . The aliphatic aldehyde monomer is a fatty acid represented by the general formula R-CHO, where R is an alkyl group containing or not containing a silicon atom, a halogenated alkyl group, an aralkyl group, or a halogenated aralkyl group. Examples include group aldehydes.
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 is dimethylaluminum(diphenyl)amide ( _CH3 ) ₂ -Al- _N10.
( _C6H5 ) ₂ , _{diethylaluminum} (diphenyl)
Amide ( _C2H5 ) ₂ -Al-N( _{C6H5 ) 2 ,} Ethylaluminum _bis (diphenyl)amide ( _C2H5 )-Al
−[N( _{C6H5 ) 2} ] _{2 ,} Ethylzinc ₍ diphenyl)amide(C2H5 ₎ -Zn-N( _C6H5 ) ₂ , Ethylmagnesium( _diphenyl )amide( _C2H5 )MgN
Examples include, but are not limited to, (C ₆ H ₅ ) ₂ and the like. Although there is no limit to the amount of the catalyst, it is appropriate to add the catalyst in an amount of 0.1 to 5 mol% relative to the aldehyde monomer mixture. When performing anionic polymerization, it is not necessary to use a polymerization medium, but if necessary, it is preferable to use a hydrocarbon such as toluene or an ethyl ether solvent. Additionally, polymerization can be carried out at a temperature in the range of 0°C to -100°C, but usually -50°C to -80°C.
A temperature of . Furthermore, the atmosphere for polymerization is preferably one in which the air in the vessel is sufficiently replaced with an inert gas such as nitrogen. The method of polymerizing the silicone-containing aldehyde-based polymer, which is one of the main components of the composition of the present invention, is not limited in any way, and may include charging an aldehyde monomer mixture onto a catalyst dissolved in an inert organic solvent. Method,
There is no problem in employing any method such as adding the catalyst itself or its solution to the aldehyde monomer itself or its solution. Next, the alkali-soluble polymer, which is another main component of the composition of the present invention, will be described. Examples of the alkali-soluble polymers include novolac resins (here, meaning condensation polymers of formaldehyde, carbolic acid, cresol, and other alkylphenols), polyhydroxystyrene resins, and the like. Novolac resins can be used in the form of homopolymer or copolymer, and polyhydroxystyrene resin can also be used in the form of homopolymer or copolymer. (hereinafter referred to as novolak resin and polyhydroxystyrene resin). These may be used alone or in the form of a mixture of both. Novolac resins and polyhydroxystyrene resins are commercially available. for example,
Examples of the novolak resin include carbolic acid novolak resin, cresol novolak resin, and carbolic acid/cresol novolak resin. Examples of the polyhydroxystyrene resin include polyparavinylphenol resin and brominated polyparavinylphenol resin. 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, the number average molecular weight should be 500 to 10,000, considering the resist film formability, heat resistance, etc.
Preferably. 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 the alkali-soluble polymer in an amount of 95 to 20 parts by weight per 5 to 80 parts by weight of the silicon-containing aldehyde polymer. 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. For 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 spin coating or dip coating. After coating, pre-baking under appropriate temperature conditions and irradiating the desired pattern with radiation causes the silicon-containing aldehyde polymer in the irradiated area to disintegrate and scatter, leaving the irradiated area with an alkali-soluble polymer. In the unirradiated area, the silicone-containing aldehyde-based polymer still prohibits the alkali-soluble polymer from being dissolved by the alkali.
A difference in solubility in a developing solution (alkaline solution) occurs between the irradiated area and the unirradiated area, making it possible to form a pattern. Examples of alkaline solutions for developers include aqueous solutions of tetraalkyl ammonium hydroxide such as tetramethylammonium hydroxide;
Examples include aqueous solutions of inorganic alkalis such as tertiary sodium phosphate and sodium hydroxide, but any alkaline solution may be used and the solution 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° C. after radiation irradiation and before development. [Examples of the Invention] Hereinafter, examples of the synthesis method of the silicon-containing aldehyde-based polymer, which is the main component of the composition of the present invention, and the synthesis method of the catalyst and monomer therefor, as well as the preparation of the composition of the present invention, will be described. Embodiments of the invention and its use will be explained step by step. Example 1 (Synthesis method of diethylaluminum (diphenyl)amide (C ₂ H ₅ ) ₂ Al-N (C ₆ H ₅ ) ₂ as a polymerization catalyst for a silicon-containing aldehyde polymer.) Stirrer, dropping funnel, three-way pot After purging the inside of a 200 ml four-necked flask with a thermometer sufficiently with nitrogen, add 33 ml of toluene to it.
14.5 g (0.127 mol) of (CH ₃ CH ₂ ) ₃ Al is introduced using a syringe through a three-way pot under a nitrogen stream. After stirring for a while to form a homogeneous solution, a solution of 21.4 g (0.127 mol) of diphenylamine dissolved in 40 ml of toluene was gradually added dropwise under ice cooling. After the dropwise addition was completed, the temperature of the reactant was raised to 60℃, and the temperature was continued for 2 hours.
The reaction was completed by stirring slowly for a while. Diethyl aluminum (diphenyl) produced
The amide (C ₂ H ₅ ) ₂ Al-N(C ₆ H ₅ ) ₂ was stored as a toluene solution in a container with a three-sided container under a nitrogen stream. Example 2 (β- of the example of silicon-containing aldehyde monomer
Synthesis method of trimethylsilylpropanal. ) In a 500 ml four-necked flask equipped with a stirrer, dropping funnel, thermometer, and condenser, add 300 ml of tetrahydrofuran and 3.04 g of finely crushed lithium.
(0.44mol), and trimethylsilyl chloride
54.25 g (0.5 mol) was added thereto, and while the liquid temperature was maintained at 0° C., 11.2 g (0.2 mol) of acrolein was added dropwise over about 1 hour while stirring, 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 (CH ₃ ) ₃ SiCH ₂ CH=CHOSi(CH ₃ ) ₃ (boiling point: 100
°C/30mmHg). Further, this was hydrolyzed by standing in hydrochloric acid-acetone at room temperature for 1 hour, and β-trimethylsilylpropanal (boiling point: 60°C/30mmHg) was obtained by distillation under reduced pressure. Examples 3 to 4 (Synthesis method of silicone aldehyde-containing polymer) Polymerization was carried out using a polymerization tube with a three-way socket. That is, into a cylindrical polymerization container with a capacity of about 100 ml under a nitrogen stream, silicon-containing aldehyde monomers and silicon-free aldehyde monomers in the proportions shown in Table 1, and toluene as a solvent were introduced using a syringe through a three-sided pot. did. The above container containing the monomer solution was heated to zero in an ice-water bath.
The catalyst (C ₂ H ₅ ) ₂ Al-N (C ₆ H ₅ ) ₂ obtained in Example 1 was gradually added to the container while cooling to 1 mol to 50 mol of the monomer. Drip. After adding the catalyst, the container is cooled to -78°C in a dry ice/acetone bath and allowed to stand for 24 hours for polymerization. After polymerization, the polymerization mixture was treated with ammoniacal methanol to decompose the catalyst, and then immersed in methanol for 1 day, filtered, washed several times with methanol, and dried under vacuum. In some cases, contrary to 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 elemental analysis. Furthermore, the monomer abbreviations TMSPA, PhPA and BA in Table 1 represent β-trimethylsilylpropanal, β-phenylpropanal and butanal, respectively.

[Table] Example 5 (Regarding the preparation and use of the composition of the present invention) Copolymer 2 of β-trimethylsilylpropanal and β-phenylpropanal obtained in Example 3
parts by weight and 8 parts by weight of poly-p-vinylphenol resin (molecular weight approximately 4000) were dissolved in cyclohexanone to prepare a 1% by weight resist solution. Next, the above resist solution was applied onto a silicon wafer and prebaked at 80°C for 20 minutes to form a 1.5 μm film.
A thick polymer film was formed. This was placed in an electron beam irradiation device, and irradiation was performed in a vacuum with an electron beam at an acceleration voltage of 20 KV at different doses. Thereafter, it was developed with a 1% by weight aqueous solution of tetramethylammonium hydroxide for about 30 seconds and washed with water. The thickness of the remaining polymer film was measured using a thin-film step meter for the areas irradiated with various different doses, and the remaining film thickness (normalized) was plotted against the electron beam irradiation dose (coulombs/cm ² ). Then, an irradiation characteristic curve showing the electron beam sensitivity characteristics was obtained. From this, the minimum irradiation dose at which the residual film rate would be zero was determined to be 2×10 ^-6 coulombs/cm ² , confirming that it is an extremely sensitive positive resist.
For example, the electron beam sensitivity of polymethyl methacrylate, a typical positive resist, is 1×10 ^-4 coulomb/
cm ² , and it was confirmed that the positive resist material of this example of the present invention exhibits a sensitivity that is approximately two orders of magnitude higher than that of polymethyl methacrylate. Next, we investigated the resistance to argon ion milling, and found that under ion milling conditions of 600V, 0.5A, and gas pressure of 2.0×10 ^-4 Torr.
The film reduction rate of this resist material was 200 Å/min. On the other hand, the film reduction rate of polymethyl methacrylate, a typical positive resist, was 500 Å/min, 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 β-trimethylsilylpropanal copolymers obtained in Examples 3 and 4 and the alkali-soluble polymer were mixed in weight proportions shown in Table 2. was dissolved in cyclohexane to prepare a resist solution of about 1% by weight according to the present invention. Coat this on a silicon wafer and
It was prebaked at ℃ for 20 minutes to form a polymer film about 2 μm thick. Next, an electron beam with an accelerating voltage of 20 KV or a soft X-ray (Molα) of 10 KW was irradiated, and the electron beam sensitivity or soft X-ray sensitivity was determined in the same manner as in Example 5. together,
Resistance to argon ion milling was also determined. These results are summarized in Table 2.

〔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. Further, the composition according to the present invention becomes alkali-soluble in the irradiated area by radiation irradiation and forms a positive pattern, so it has excellent performance as a positive electron beam resist that forms a high-resolution pattern. Therefore, the composition according to the present invention can be used to form patterns for manufacturing electronic components such as semiconductor devices, magnetic bubble memory devices, integrated circuits, etc., with remarkable effects.

Claims (1)

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