JPS5868745A - Production of relief structural body - Google Patents

Abstract

PURPOSE:To obtain a relief structural body of high resolution with less radiation dose and high accuracy by irradiating radiations to a thin film of an alpha-substituted acrylate polymer material then developing the same. CONSTITUTION:A thin film consisting of an alpha-substituted acrylate polymer material is formed on a substrate and after radiations are irradiated to the desired parts thereof, the irradiated parts are dissolved and developed with an alkali developing soln. For example, an alpha-substituted acrylate polymer material such as poly(alpha,alpha-dimethyl benzyl methacry late) poly(alpha-methyl benzyl acytate) or the like is dissolved in a solvent such as toluene and the soln. is coated on a substrate. After the coating is exposed by electron rays, the same is developed with an alcohol soln. of sodium alcoholate, an alcohol soln. of org. basic materials such as pyridine or a soln. of inorg. basic materials such as sodium hydroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing embossed structures, and an improved method for forming fine patterns applied to semiconductor devices, magnetic bubble memories, integrated circuits, etc. be.

Conventionally, methods using photoresists sensitive to ultraviolet or visible light have been widely put into practical use as pattern forming methods for manufacturing electronic components such as semiconductor devices and magnetic bubble memory devices. For the purpose of achieving higher density and higher integration, there is a need for a method for forming patterns with a width of 1 μm or less. However, with the above method of using light, it is extremely difficult to accurately form a pattern with a width of 1 μm or less due to the unique properties of light such as diffraction, scattering, and interference, and at the same time, the yield decreases. Also, the method using light mentioned above is 17+
This was not suitable as a method for forming a pattern with a width of m or less.

In response to this, recently, instead of the 7J etching technology that performs fine processing using visible light, high-energy technologies such as electron beams, X-rays, and ion beams have been introduced. As a result of the development and research of radiation lithography technology, materials that are sensitive to -lx radiation have been extensively tested.In particular, radiation irradiation has caused Positive radiation-sensitive organic polymer materials that induce a chain scission reaction and make the irradiated part soluble in a developer to form a pattern, such as poly(methyl methacrylate), poly(1-butenesulfone), etc. is the radiation σ
) Crosslinking by irradiation 1. Compared to negative-tone sensitive organic abrasive materials, which induce Q reaction and become insoluble in the irradiated area to form a pattern, the gamma value obtained from the sensitivity characteristic curve is large, making it possible to create high-resolution patterns. It is extremely convenient as a resist material for microfabrication. However, the sensitivity of positive-tone sensitive organic polymeric materials, including the materials mentioned above, is lower than that of negative-tone ones, ranging from 1 to 10%.
1000, the time required for pattern formation was long, and it was impractical.

It should be noted that when positive resist materials such as poly(methyl methacrylate) mentioned above are irradiated with radiation, they induce a main chain scission reaction in the polymer chain, resulting in a decrease in the number of molecules, and as a result, the irradiated area becomes organic. It dissolves easily in the developer, and this is used to form batts. However, in order to create a difference in solubility by utilizing a difference in molecular weight, a large amount of radiation is required, which is one reason why positive resist materials have low sensitivity.

The present invention aims to eliminate the above-mentioned drawbacks of the prior art and provide a method for manufacturing a relief structure with a low dose of radiation, a high degree of fIv, and a high resolution.

In order to achieve the above objective, the Ministry of the Invention and others have conducted a comprehensive examination of organic IQ1 molecular materials and development methods that are thought to have radiation sensitivity. Form a thin film on a substrate, irradiate a desired part of the thin film with radiation from this sieve, and then elute and develop the irradiated part with an alkaline developer. I discovered that it would be sufficient to manufacture a carved structure.

The α-substituted acrylic acid ester polymer materials used in the present invention are 1 to 1 (where RI represents a methyl group, an ethyl group, a TL-propyl group, or a phenyl group, and R2 represents hydrogen, an alkyl group, an aryl group, group or an aralkyl group (argyl group substituted with an aryl group), R8 is hydrogen, an alkyl group,
Represents an aryl group, an aralgyl group, or a halogen atom. 1 represents a numerical value indicating the degree of polymerization. ) (In the formula, R1 represents a methyl group, ethyl group, n-propyl group, or phenyl group, and R2 is an alkyl group.

It represents an aryl group or an aralkyl group, and R8 represents hydrogen, an alkyl group, an aryl group, an aralgyl group, or a halogen atom. 1 represents a numerical value indicating the degree of polymerization. ) or 2 (wherein R7 represents a methyl group, ethyl group, TL-propyl group, or phenyl group, and R2 represents an alkyl group, aryl group, aralgyl group, or a substituent containing a heteroatom such as nitrogen, oxygen, sulfur, etc.) represent.

1 represents a numerical value indicating the degree of polymerization. ) was used. The polymers represented by the above general formulas +1), f2+ and (3) are used as a homopolymer or a copolymer of two or more monolayers.

In other words, the above-mentioned compound induces a polymer chain scission reaction by irradiation with high-energy radiation such as electron beams, X-rays, and ion beams, and also contains carboxylno/... As a result, the irradiated part becomes soluble in the alkaline solution, so only the irradiated part of the 5 alkaline earth metal is eluted and developed, producing a high-resolution positive relief structure. can do.

For example, in general formula (2) described above (polymethacrylic acid α,α-dimethylbenzi), R5 represents a methyl group,
7 represents a methyl group and R5 represents hydrogen) is irradiated with an electron beam,
The figure below shows the changes in the infrared absorption spectrum when That is, the infrared absorption spectrum of polymethacrylic acid α,α-dimethylbenzyl before electron beam irradiation is as shown in (1) of the figure, and 16 x
When electron beam irradiation of 10-'9ca is performed, (2
As shown in 1K, 1729, 1132, 764 and 7
The absorption characteristic of polymethacrylic acid α,α-dimethylbenzyl of 00crn' decreases, and instead the absorption of 1707, 1175 and 1265m-' characteristic of polymethacrylic acid appears, and f carboxyl, l (-, - C
It was confirmed that OOH) was generated. In addition, in the figure (
3) is an infrared absorption spectrum of polymethacrylic acid synthesized separately and is listed as a reference. Since the polymer containing methacrylic acid units produced by electron beam irradiation is alkali soluble, only the electron beam irradiated areas can be selectively removed by alkaline development, resulting in a positive relief structure. b).

Next, a) 4' charges conveniently used in the present invention will be explained.

The α-substituted acrylic acid ester polymer used in the present invention can be obtained as follows.

That is, the general formula ((i)2R2 (,'ll,, = C /,' = 0) (wherein R8 represents a methyl group, ethyl group, +1-propyl group, or phenyl group, and l?2 is hydrogen , represents an argyl group, an aryl group, or an aralgyl group (an alkyl group substituted with an aryl group), R3 is hydrogen, an alkyl group,
Represents an aryl group, an aralkyl group, or a -.rogen atom. R1 General formula ■: CH,,, C -0 (In the formula, R1 is a methyl group, ethyl group, n-propyl group, or phenyl group) and R2 is an alkyl group.

It represents an aryl group or an aralkyl group, and R3 represents hydrogen, an alkyl group, an aryl group, an aralkyl group, or a -.rogen atom. -n-+t-M-＠degree-wo-moeshisu one-several-tall bales m-) R1 or CH=C General formula ((?): C= O〇, d (in the formula, R1 represents a methyl group, ethyl group, leupropyl group, or phenyl group, and 11. represents an alkyl group 7 I)-
represents a 1-substituent group containing a heteroatom such as an aralkyl group, an aralkyl group, or a heteroatom such as nitrogen, oxygen, or sulfur.

It represents a numeric value indicating the degree of success. A polymer material obtained by vinyl polymerizing one or more of the monomers shown in ) by radical polymerization or ionic polymerization is used.

In addition, when copolymerizing the monomers shown in the general formulas (/P), (1 and C) above, any composition can be used. , Inbunalene, etc. can be copolymerized with addition-polymerizable monomers having a C1l, =C group that does not form a carboxyl group in the polymer vehicle (1'/:) by irradiation with radiation. The copolymerization composition is the general formula CI
), (#) or (C') in an amount of in to 999 molt. In cases where the number of patients is less than 10, the amount of radiation exposure after radiation
((The solubility of the alkali IJ El in the side part is low, and as a result, the radiation sensitivity is low, making it difficult to put it into practical use.

Examples of the alkaline developer used in the method for producing a relief structure of the present invention include an alcohol solution of sodium alcoholade, a solution of an organic basic substance such as pyridine, piperidine, trimethylamine, and triethylamine dissolved in alcohol, or a hydroxide developer. ) A solution prepared by dissolving an inorganic basic substance such as IJum or tetramethylammonium hydroxide in water, alcohol, etc. should be used.

An example of synthesis of materials used in the present invention and examples of the present invention will be described below.

Synthesis Example 1 Put 250+++/ml of ethyl ether into a 61-sized three-necked flask equipped with a stirrer, a condenser, and a dropping funnel α, α-
139 q of dimethylbenzyl alcohol and 250 ml of triethylamine were added and stirred, and a mixed solution of 155 q of methacrylic acid chloride and 200 ml of ethyl ether was added dropwise from the dropping funnel over about 5 hours. After the dropwise addition, the flask was heated in a water bath while stirring, and the reaction mixture was heated to about 5
Refluxed for an hour.

After reflux, 500 m/! of water! Add 'f and stop the reaction 1-
Decanting the etheric layer, dividing it into parts 1,
The mixture was washed six times with a saturated aqueous ammonium chloride solution and then three times with a saturated aqueous sodium carbonate solution (2).Finally, anhydrous sodium sulfate was added to the above ether solution and left overnight [2] to dry. After separating the desiccant, ethyl ether was distilled off and vacuum evaporated 6? (From VC methacrylic acid α, (χ-dimethylbenzyl (boiling point = 58-61 °C / 06 m㎖11.q
) 129, get q.

Synthesis Example 2 200 ml in a 31 three-necked flask equipped with a stirrer, a condenser, and a dropping funnel! of ethyl-C-ter, 129y of 1-phenylethanol and 200m of triethylamine.
/! was added and stirred, and a mixed bath solution of 130q of methacrylic acid chloride and 200me of ethyl ether was added dropwise from the dropping funnel over about 2 hours. After the dropwise addition was completed, the flask was heated in a water bath while stirring, and the reaction mixture was refluxed for about 10 hours, followed by 500 m7 of water. was added to stop the reaction, the ether layer was separated by decantation,
It was washed 6 times with a 5% aqueous solution of hydrochloric acid, then 5 times with a 10% aqueous solution of sodium bicarbonate, and finally, anhydrous sulfuric acid (IJ) was added to the above ether solution and left overnight to dry. After separating the desiccant, ethyl ether was distilled off, and α-methylbenzyl methacrylate (boiling point: 60-b) was distilled off under reduced pressure. The procedure was similar to that described in 2.

Note that one synthesis scheme is as follows.

2 (However, R7 represents an argyl group, an aryl group, an aralkyl group, or a halogen atom.)
methacrylic acid chloride was added dropwise to the mixture under stirring in 1-(mono-substituted) ethanol and triethylamine ether to carry out a dehydrochlorination reaction, thereby yielding 1-(mono-substituted phenyl)ethyl methacrylate.

Synthesis Example 4 The synthesis of 1-menal-1-(monosubstituted phenyl)ethyl methacrylate was carried out in the same manner as in Synthesis Examples 1-2. /fThe synthesis scheme is as follows.

(However, R1 represents an alkyl group, an aryl group, an aralgyl group, or a halogen atom.) That is, 1-
Methyl-1-(mono-substituted phenyl)ethanol and triethylamine were stirred in ether, methacrylic acid chloride was added dropwise thereto, and a dehydrochloric acid reaction was carried out to produce 1-methyl-1-(mono-substituted phenyl methacrylate). ) Ethyl was obtained.

Synthesis Example 5 Diphenyl carbinol 15B,q, trietheramine 1G6. q, 240 ml of dry ether and 24, q of cuprous chloride were added, and a mixed solution of 94 q of methacrylic acid chloride and 240 ml of dry ether was added from the dropping funnel over about 1 hour while stirring. Thereafter, the mixture was heated under reflux for 6 hours to react. Supernatant 0) After separating the ether solution of the reaction product, the product in the remaining solid was diluted with ether to 71 L! I Extract 1~ Both ether solutions were combined and washed four times with 300 g of water. This washing solution was extracted two times with 150ml of ether, combined with the ether solution of 911 people, and extracted once again with 300ml of water, then 3 times with 300ml of 2N hydrochloric acid, and further extracted with KO, 7N-hydrochloric acid. sodium carbonate 6
After washing twice with 00ml, it was dried overnight with 5Q7 anhydrous magnesium sulfate. The ether was eluted from this solution to obtain a sum crystal of diphenylmethyl methacrylate. This was crystallized from petroleum ether, and then +Q crystallized from rohegizan to obtain purified diphenylmethyl methacrylate 132 (melting point: 78-79°C).

Synthesis Example 6 The α,α-dimethylbenzyl methacrylate 5z obtained in Synthesis Example 1 was polymerized using azobisisobutyronitrile 0041 as a polymerization initiator at 60°C for 10 hours.

Bulk polymerization was carried out. The polymerization was carried out in a sealed tube filled with N and gas.

The obtained polymer was added to about 20 ml of toluene at fR%A'L.
After filtering through a glass filter to remove small amounts of insoluble matter, the mixture was poured into about 500 ml of methanol to yield a white powdery polymer. The average molecular weight of this) J'' combination was determined by liquid chromatography and was approximately 1.2 million in terms of polystyrene.

Synthesis Example 7 α-Methylbenzyl methacrylate 51 obtained in Synthesis Example 2 was subjected to bulk polymerization at 60° C. for 10 hours using 0.04y- of azobisisobutyronitrile as a polymerization initiator. The obtained polymer was purified in the same manner as in Synthesis Example 6 to obtain poly(α-methylbenzyl methacrylate) having a weight average molecular weight of approximately 1.5 million.
I got it.

Example 1 Poly(α, α-dimethylbenzyl methacrylate) obtained in Synthesis Example 6 was dissolved in toluene to prepare a 5M resist solution. Subsequently, the above resist solution was spin-coated onto a silicon wafer at 1000y7:+yn to form a 0.7 μm thick polymer film. This was prebaked at 90°C for 30 minutes, then placed in an electron beam irradiation device, and exposed to an electron beam at an acceleration voltage of 2o and KV in vacuum, with an irradiation dose of 1 x io-'coulombs/~. After irradiating a predetermined area of the molecule coating, it is then taken out from the above apparatus and developed by immersing it in an alkaline developer consisting of a 53J-+:% methanol solution of sodium methylate for 6 minutes, followed by rinsing with methanol. A resist pattern was formed by removing the irradiated portion of the polymer film, and a line and space of 05 μm was resolved, confirming high resolution.

Also, to find the sensitivity to electron beams.

When irradiating with the individual Q) irradiation amount and determining the minimum irradiance at which the film thickness becomes zero after the image, it is axio-6 coulomb 4 broom when using the above-mentioned alkaline developer, On the other hand, when an organic developer consisting of methyl isobutyl ketone-inpropyl alcohol (1:3 volume ratio) is used, the result is 7SX10-'coo[1 n/crA, and when alkaline development is performed, the sieve sensitivity becomes extremely high. It has been confirmed that this resist has a sensitivity of 1 or more times higher than that of polymethyl methacrylate, which is a typical positive resist.

Example 2 The poly(α-menalbenzyl methacrylate) obtained in Synthesis Example 7 was made into a 6 M toluene solution, and a 1 μm thick polymer film was formed on a silicon wafer in the same manner as in Example 1. Then, after prebaking at 90°C for 30 minutes, it was irradiated with an electron beam at an acceleration voltage of 2QKV, and developed with a 5% methanol solution of sodium methylate. −'Coulomb/′−
It was confirmed that the gamma value, which indicates contrast, was a very high 5, and the resolution was excellent.

Furthermore, the above sample (silicon wafer coated with a resist film thickness of 1 μm) was subjected to an electron beam irradiation amount of 8×10-coulombs/d.
A resist pattern was formed by irradiating a predetermined area with , then taking it out from the above-mentioned apparatus, developing with a 5% methanol solution of sodium methylate, and rinsing with methanol. was resolved, and a high-resolution pattern was obtained.

Examples 3 to 8 Radiation-sensitive polymer materials of each shield composition were synthesized in the same manner as in Synthesis Examples 6 and 7, and dissolved in toluene in the same manner as in Examples 1 and 2 to prepare resist solutions. This was spin-coated onto a silicon wafer to form a polymer film about 1 μm thick.

Next, the electron beam with an accelerating voltage of 2aK/' is applied with an accelerating voltage of 1
Wavelength 42A0 from 0KV rotating water-cooled silver 71 cathode
irradiation using soft X-rays and alkaline development. A resist pattern was formed. The results are summarized in Table W, and it was confirmed that high-resolution relief structures were obtained in all cases.

Example 9 Silicon wafer prepared in the same manner as in Example 1.
A thin film with a thickness of m is irradiated with T11 radiation, and an alkaline developer such as a developer consisting of a 5% methanol solution of triethylamine or a 511:1 solution of sodium hydroxide is applied.
- A developer consisting of a methanol solution of steamed rice or 5'h1 class % of tetramethelammonium hydroogizide
The irradiated area was dissolved and removed using a developer consisting of an aqueous solution.

In this way, a resist++ pattern was formed, but
When using the above-mentioned developer, each IX10-4
C'/, 11, 2X10-'C7', 11, 2X
Lines and spaces of 05 to 1.0 μm were resolved with an electron beam irradiation dose of 1o-'C7,4.

Comparative Example 1.2 Radiation-sensitive polymeric materials of various compositions (but not according to the present invention) were synthesized in the same manner as in the examples, subjected to electron beam irradiation in the same manner as in the examples, and subjected to alkaline development. A resist pattern was formed. The results are shown in the table, but the sensitivity to electron beams in this comparative example was low, and it was not possible to produce a relief structure that could be put to practical use.

As is clear from the above description, according to the present invention, it is highly sensitive to radiation such as electron beams, Relief Structure 2 A dead body can be manufactured, and it has a remarkable effect on the manufacture of ultra-fine semiconductors.

[Brief explanation of drawings]

The figure shows the infrared absorption spectrum of polymethacrylic acid α,α-dimethylbenzyl before and after electron beam irradiation,
This shows the infrared absorption spectrum of polymethacrylic acid. 1-6: Infrared absorption spectrum agent Patent attorney Su 1) Li Xin 6

Claims (1)

[Claims] A thin film made of an α-substituted acrylic acid ester polymer material is formed on a substrate, a desired portion of the thin polymer film is irradiated with radiation, and then the irradiated portion is eluted and developed with an alkaline developer. A method for manufacturing an embossed structure.