JP3026198B2 - Pattern forming material for electron beam irradiation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel pattern forming material for electron beam irradiation. More specifically, the present invention relates to a pattern forming material for electron beam irradiation capable of performing fine processing with high resolution and a high aspect ratio on the order of nanometers by a lithographic method using an electron beam.

2. Description of the Related Art Conventionally, in a manufacturing process of a semiconductor element such as an IC or an LSI, fine processing by a lithographic method using a photoresist has been performed. this is,
This is a method in which a thin film of photoresist is formed on a substrate such as a silicon wafer, an image is formed by irradiating the thin film with actinic rays, and then the substrate is etched using a resist pattern obtained by developing as a mask.

In recent years, the degree of integration of semiconductor devices has rapidly increased, and fine processing with high precision has been required. Along with that, the actinic rays used for irradiation are also electron beams,
Excimer lasers, X-rays and the like have begun to be used.

As a negative electron beam resist sensitive to an electron beam, a novolak-based organic polymer electron beam resist or the like is generally used. However, in this negative type organic polymer electron beam resist, the organic polymer compound used in the resist is cross-linked by electron beam irradiation,
Since the pattern is formed by the principle that the irradiated portion is insoluble in the developing solution, a pattern smaller than the molecular size of the polymer compound cannot be formed. The molecular size of this polymer compound is usually about 10 nm, and the resolution is several tens of nm or more. In recent fine processing on the order of nanometers, development of a resist having a higher resolution has been desired.

On the other hand, a conventional negative-type organic polymer electron beam resist has a resistance to dry etching of 10 n
When performing fine etching on the order of m, it is not possible to process a fine pattern with a high aspect ratio unless a complicated method of transferring to another material having dry etching resistance by lift-off or etching is used. was there.

[0006] In recent years, a new carbon material "fullerene" having a hollow structure represented by a soccer ball type molecule C60 comprising 60 carbon atoms has been found, and researches for its physical properties and functions have been actively conducted. . Various properties of fullerenes have been found one after another, and they have been applied to functional plastic materials, catalysts, pharmaceuticals, etc., including the electronics field, but they have been used for electron beam resists. Did not.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a novel electron beam irradiating pattern forming method capable of performing fine processing with a high resolution and a high aspect ratio on the order of nanometers by a lithographic method using an electron beam. It is intended to provide materials.

[0008]

The present inventors have SUMMARY OF THE INVENTION may be alternative to conventional resist materials, the results of extensive research in order to develop a high resolution pattern forming material, C ₆₀ or C ₇₀
Fullerenes are soluble in organic solvents, but when they are irradiated with an electron beam, they have been found to be graphitized and become insoluble in organic solvents.The present invention utilizes this electron beam irradiation effect. And the fact that it can be used as an electron beam sensitive resist, and the molecular size of fullerene is very small at 1 nm or less,
This is based on the finding that high resolution can be expected. That is, the present invention forms a thin layer made of fullerene on a substrate, and then, after irradiating an electron beam, treating with a solvent to remove an unexposed portion to form a fine pattern, and It has been confirmed that a fine pattern having a high aspect ratio can be formed with high resolution and can be easily formed by performing a dry etching process using the fine pattern obtained as a mask, thereby completing the present invention. It is.

That is, the present invention provides a pattern forming material for electron beam irradiation, wherein a fullerene thin film layer is provided on a substrate.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The substrate in the pattern forming material for electron beam irradiation according to the present invention is not particularly limited, and is commonly used for forming a fine pattern by a lithographic method, for example, a silicon wafer, a nitride, or the like. Silicon, gallium-arsenic, aluminum, indium,
One having a coating such as titanium oxide can be used.

Further, fullerene, which is a material of the fullerene thin film layer provided on the substrate, has, for example, carbon atoms 6
A soccer ball type C _{60 having} zero carbon atoms and a rugby ball type C _{70 having} 70 carbon atoms are known. Among them, C ₆₀ is particularly preferable from the viewpoint of practicality.

To provide a fullerene thin film layer on a substrate,
A conventional film forming method, for example, a vacuum evaporation method or a sputtering method, or a coating solution is prepared by dissolving fullerene in an appropriate solvent, and this is coated on a substrate with a spinner or the like,
A drying method or the like can be used. The thickness of the fullerene thin film layer is usually selected in the range of 1 to 100 nm.

In the pattern forming method using the pattern forming material for electron beam irradiation according to the present invention, the electron beam is applied to the fullerene thin film layer provided on the substrate in accordance with a predetermined pattern shape or through a predetermined mask pattern. Is irradiated. In this case, the irradiation amount of the electron beam differs depending on the type of the organic solvent used as the developing solution, and cannot be determined unconditionally.
× ^10-3 C / cm ² or more, preferably 1 × ^10-2 C / c
m ² or more. The upper limit is not particularly limited, but is practically 10 ² C / cm ² , preferably about 10 C / cm ² .

After irradiating the electron beam in this way,
Develop using an organic solvent. Examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; aliphatic halogenated hydrocarbons such as methylene dichloride, ethylene dichloride, chloroform, and carbon tetrachloride; and aromatic halogenated hydrocarbons such as monochlorobenzene. Hydrogen and the like. These may be used alone or as a mixture of two or more, but monochlorobenzene alone is particularly preferred from the viewpoint that there is little residue in the unexposed portion after the development processing and the contrast is good. Good.

When the fullerene thin film layer is irradiated with an electron beam, the irradiated portion is graphitized, so that the solubility in the organic solvent is significantly reduced. Therefore, if development processing is performed using this organic solvent, the non-irradiated portion is selectively dissolved and removed, leaving only the irradiated portion, and a resist pattern faithful to the original image is formed. The development processing is usually performed by a conventionally used immersion method, but a brush-out method or a spraying method can also be used.

Since the resist pattern thus formed is graphitized, it has a low sputter rate to ion irradiation, a high chemical resistance to plasma containing chlorine and fluorine, and a dry etching resistance. Therefore, the substrate can be etched with high accuracy using this resist pattern as a mask.
As the etching treatment of the substrate, dry etching treatment is preferably used, and in particular, dry etching treatment using an electron cyclotron resonance (ECR) etching apparatus is suitable. In this manner, a fine pattern having a high aspect ratio is easily formed with high resolution.

[0017]

The pattern forming material for electron beam irradiation according to the present invention is provided with a fullerene thin film layer which is an electron beam sensitive layer. By using this, a favorable sensitivity and a nanometer order can be obtained. Fine processing with a high aspect ratio becomes possible. Further, when a pattern is formed by using the electron beam irradiation pattern forming material of the present invention, a fine resist pattern excellent in dry etching resistance on the order of nanometers faithful to the original image can be efficiently formed.

[0018]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0019] Example 1 C ₆₀ fullerene (99% purity) powder and heated to 500 to 700 ° C. at 10 ^@ 4 Pa in a vacuum, and deposited to a thickness of 70nm at 5 minutes on a silicon substrate, a fullerene thin film A layer was formed. Next, a 200 keV electron beam was applied to the thin film layer at 0.024 C / cm ² and 0.012 C / cm ^2.
After irradiating with each of the above amounts, they were immersed in monochlorobenzene, developed, and then rinsed with isopropyl alcohol.

FIG. 1 is a graph showing the relationship between the amount of electron beam irradiation, the development processing time for an unirradiated sample, and the residual film pressure. As apparent from FIG. 1, is irradiated with an electron beam C ₆₀ fullerene thin film layer, it can be seen that the dissolution rate in monochlorobenzene is delayed. In this example, if the substrate is immersed in monochlorobenzene for 10 seconds, only the portion not irradiated with the electron beam can be selectively removed and the irradiated portion can be left.

Example 2 In the same manner as in Example 1, a 70 nm thick silicon substrate was formed.
C ₆₀ to form a fullerene thin film layer. Next, the thin film layer was irradiated with a predetermined amount of an electron beam of 20 keV in a range of 0 to 0.1 C / cm ² , developed with monochlorobenzene for 1 minute, and then rinsed with isopropyl alcohol for 10 seconds. Similarly, after developing with a mixed solvent of monochlorobenzene and isopropyl alcohol at a weight ratio of 1: 4 for 7 minutes, isopropyl alcohol was added for 10 minutes.
Rinse treatment for 2 seconds.

FIG. 2 is a graph showing the relationship between the irradiation amount of electron beam (20 keV) and the remaining film thickness when each developing solution is used. As is apparent from FIG. 2, when developed with monochlorobenzene for 1 minute, the sensitivity is 1 × ^-2 C / cm ² . On the other hand, when developed for 7 minutes with a mixed solvent of monochlorobenzene and isopropyl alcohol, 5 × 10 ⁻³
It has a sensitivity of C / cm ² , which is better than the former, but the contrast is better when using the former developer.

Example 3 In the same manner as in Example 1, a 70 nm-thick
After forming a C60 fullerene thin film layer, the thin film layer was irradiated with an electron beam of 20 keV at 0.01 C / cm ² . Then, this was developed with toluene and monochlorobenzene for 1 minute each, and the two were compared. As a result, the residue in the unirradiated portion was more developed with toluene, and monochlorobenzene was more excellent as a developing solution. I knew it was.

[0024] C ₆₀ fullerene was adjusted coating liquid was dissolved in monochlorobenzene, by coating and drying by spin coating on a silicon substrate to form a thin fullerene film layer having a thickness of 5 nm. Next, the thin film layer was irradiated with an electron beam of 20 keV at 0.02 C / cm ² , developed with monochlorobenzene for 1 minute, and rinsed with isopropyl alcohol for 1 minute. Was.

Embodiment 5 In the same manner as in Embodiment 1, a 70 nm-thick
C ₆₀ After forming the fullerene thin film layer, the thin film layer using an electron beam of 20keV to, drawing the string of a dot pattern of 20nm at dose of ^{2 × 10 -2 C / cm 2} . Next, after developing with monochlorobenzene for 1 minute, rinsing with isopropyl alcohol for 10 seconds, a resist pattern composed of rows of dots having a diameter of 20 nm was formed.

Next, this sample is placed in an electron cyclotron resonance (ECR) etching apparatus, and dry etching is performed using the resist pattern as a mask (sample temperature -130 ° C., etching SF ₆ 1 × 10 ⁻⁴ torr, microwave : 2.45 GHz, 250 W, sample 20 nm,
A high aspect ratio silicon pillar having a height of 160 nm was formed.

[0027] To examine the Example 6 dry etching resistance, in the same manner as in Example 1, in the thin film layer after forming the fullerene thin layer of C ₆₀ with a thickness of 70nm on a silicon substrate with an electron beam of 20 keV 2 It was irradiated with × 10 ^-2 C / cm ² and developed with monochlorobenzene for 1 minute.

On the other hand, for comparison, a novolak-based resist, SAL601 (manufactured by Shipley Co.) was spin-coated on a silicon substrate and dried to form a 300-nm-thick resist layer. 20k
An electron beam of eV was irradiated at 25 μC / cm ² and developed.

Next, each was put into an ECR etching apparatus and subjected to a dry etching process (etching conditions: room temperature, etching gas SF ₆ × 10 ⁻⁴ torr, microwave: 2.45 GHz, 250 W, 13.56 MH for the sample).
z high frequency 5 W was applied).

[0030] As a result, the ratio of the etching rate of C ₆₀ of silicon whereas at 10 times or more, the ratio of the etching rate for SAL was 4 times. That is, C
It can be seen that ₆₀ has more than twice the dry etching resistance compared to SAL. This indicates that a fine pattern having a high aspect ratio can be formed by using the pattern forming material of the present invention.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the amount of electron beam irradiation and the development processing time and the remaining film thickness in a non-irradiation test in Example 1.

FIG. 2 is a graph showing the relationship between the amount of electron beam irradiation and the remaining film thickness when using each developer in Example 2.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-7-134413 (JP, A) JP-A-7-33751 (JP, A) JP-A-6-167812 (JP, A) JP-A-6-167812 19136 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F ^7/ 00-7/42

Claims (2)

(57) [Claims] An electron beam irradiation pattern forming material comprising a substrate and a fullerene thin film layer provided on a substrate. 2. A fullerene electron beam irradiation pattern forming material according to claim 1 wherein the C _60.