JP2003140356A - Method for forming fine pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a fine pattern by which processing with high accuracy and high reliability is realized in the formation of a fine pattern on a substrate to be processed such as a semiconductor substrate. SOLUTION: The method for forming a fine pattern includes processes of depositing a mask material 20 on a pattern formed on the surface of a second resist film 3 on the objective substrate 1 and then removing a first resist film 2 and the second resist film 3 to form the arrangement of a dot pattern 25 made of the mask material 20 on the objective substrate 1. This method is characterized in that the mask material 20 used contains fine particles having aggregates of carbon atoms as the structural element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine pattern forming method used for manufacturing information recording / processing devices and the like.

[0002]

2. Description of the Related Art Various types of information recording / processing devices such as a compact disk are manufactured by utilizing an array of fine and high-density dot patterns. Conventionally, such a fine dot-shaped pattern array is formed by inverting the hole-shaped pattern using a pattern inversion method called a lift-off method. FIG. 3 shows a fine pattern forming process based on the conventional lift-off method.

First, as shown in FIG. 3A, after coating a first resist film 2 and a second resist film 3 on a substrate 1 to be processed, high energy such as electron beam, ultraviolet ray or X-ray is applied. Irradiate line 4. Then, the first resist film 2 and the second resist film 3 in the irradiated portion are removed by developing with a developing solvent. As a result, FIG.
As shown in FIG. 2, the hole pattern 10 in which the second resist film 3 has an overhang shape with respect to the first resist film 2.
To form.

The reason why the hole pattern 10 has the overhang shape is that the mask material adhesion region on the second resist film 3 is separated from the adhesion portion on the substrate 1 to be processed, that is, the portion to be the dot pattern, and lift-off described later is performed. This is to facilitate the process. If a resist having a high sensitivity to the high energy rays 4 (first resist film 2) is used as a lower layer and a resist having a low sensitivity (second resist film 3) is used as an upper layer, the opening of the upper resist film is opened. The part is smaller than that of the lower layer, and an overhang pattern is easily obtained. Further, it is possible to form the overhang-shaped hole pattern 10 as described above even with a single-layer resist film. However, in the case of forming a high density dot pattern on the nanometer level, a two-layer resist film that can surely obtain an overhang shape is advantageous.

Next, as shown in FIG. 3C, the overhang-shaped second resist film 3 and the substrate 1 to be processed 1 are formed.
A mask material 5 serving as a mask used for processing the substrate 1 to be processed is attached to the top. As the mask material 5, a material having high resistance to the etching gas of the dry etching used for processing the substrate 1 to be processed is used. As a method for attaching the mask material 5, usually, electron beam vapor deposition, vacuum vapor deposition, or sputtering method can be used. Further, as the material of the mask material 5, a metal such as nickel or titanium is used from the viewpoint of high dry etching resistance.

Next, the entire substrate 1 to be processed is dipped in a resist stripping solution (solvent for resist removal) to dissolve and remove the first resist film 2 and the second resist film 3. On this occasion,
The mask material 5 attached on the second resist film 3 is removed together with the first resist film 2 and the second resist film 3 (this is generally called lift-off). As a result, as shown in FIG. 3D, a dot pattern made of the mask material 5 is formed on the substrate 1 to be processed.

Next, the dot-shaped mask material pattern 5 is
Using the mask for processing the substrate 1 to be processed, the region of the substrate 1 to be processed exposed from the mask is etched. As a result, as shown in FIG. 3E, a predetermined dot-shaped pattern array 25 is formed on the surface of the substrate 1 to be processed. After the processing is completed, the mask material 5 is not necessary in most cases, so the mask material 5 used as the mask is removed as shown in FIG. Here, an inorganic acid such as hydrochloric acid is usually used for removing the mask material 5 such as metal.

[0008]

However, the above-mentioned conventional fine pattern forming method has the following problems. First, a metal such as nickel or titanium is used as the mask material 5, but an inorganic acid such as hydrochloric acid must be used for peeling the processed substrate 1 after processing, as described above. For this reason, in the conventional fine pattern forming method, in many cases, the substrate 1 is eroded by the inorganic acid together with the mask material 5, so that only the metal of the mask material 5 is damaged without damaging the substrate 1. It was difficult to peel off.

Further, in the conventional fine pattern forming method, as a method of depositing the metal as the mask material 5 on the second resist film 3 having an overhang shape, a vapor deposition method such as electron beam evaporation, vacuum evaporation, or sputtering is used. The phase method is used. However, since the mask material 5 adheres to the surface of the second resist film 3 in the form of particles, variations occur in the particle size and the particle number distribution with respect to the incident direction.

That is, in the conventional fine pattern forming method,
As shown in FIG. 3C, the dimension and the film thickness of the mask material 5 that passes through the opening of the overhang-shaped hole pattern 10 and adheres to the surface of the substrate 1 to be processed are within the surface of the substrate 1 to be processed. There is a problem in that it becomes non-uniform and it is difficult to process the substrate 1 to be processed with high precision. Further, in the conventional fine pattern forming method, the temperature of the particles of the mask material 5 becomes high in the above-mentioned various vapor phase methods, so that the first resist film 2 and the second resist film 3 are formed in the mask. There is also a problem that the particles of the material 5 are thermally damaged, the overhang pattern of the hole pattern 10 is deformed, and the processing accuracy of the substrate 1 to be processed is reduced.

An object of the present invention is to provide a fine pattern forming method which solves the above-mentioned problems in forming fine patterns on a substrate to be processed such as a semiconductor substrate and realizes highly accurate and highly reliable processing. is there.

[0012]

In order to solve the above-mentioned problems, the invention according to claim 1 removes the resist film after depositing a mask material on a pattern formed on the resist film on the substrate. A fine pattern forming method for forming a pattern made of the mask material on the substrate by
There is provided a fine pattern forming method, wherein the mask material is fine particles having (or containing) an aggregate of carbon atoms. The invention according to claim 2 is characterized in that, in the fine pattern forming method according to claim 1, the fine particles are one or both of fullerene and a fullerene derivative.

Further, the invention according to claim 3 is the method for forming a fine pattern according to claim 1 or 2,
It is characterized by including a mask attaching step of attaching the mask material by a spin coating method. Further, the invention according to claim 4 is the method for forming a fine pattern according to any one of claims 1 to 3, further comprising a step of irradiating with a high energy ray (for example, ultraviolet ray) after the step of attaching the mask. It is characterized by

Regarding the high etching resistance effect of the aggregate of carbon atoms, Applied Physics Letters (Ap
pl. Phys. Lett. ), Vol. 48 (13), pp. 835-837 (1986), as compared with a novolac resin-based resist which is the resist material having the highest etching resistance against oxygen plasma dry etching. However, it has been shown that a film composed of an aggregate of carbon atoms is approximately twice as resistant as it is.

As described above, fullerenes can be used as the fine particles containing the aggregate of carbon atoms as a main constituent element. Fullerenes in which carbon atoms have a spherical shell-like molecular structure include various forms called fullerenes such as C36 and C60. The fullerenes include high-order fullerenes having 60 or more carbon atoms, long nanotubes formed of one kind of high-order fullerenes, and metal-containing fullerenes in which a metal is incorporated into the spherical shell-like molecular structure. .

Among these fullerenes, those having a molecular volume as small as possible are preferable from the viewpoint of improving the resistance by increasing the density. Further, a fullerene derivative in which an atom such as hydrogen or oxygen, a methyl group or an amino group is bonded to a carbon atom of fullerene is also effective in increasing etching resistance.
Further, any fullerene derivative can be used in principle, but from the viewpoint of improving the resistance by increasing the density, a fullerene derivative having a functional group that is as small as possible and has solvent solubility is most suitable. .

In the present invention, a mixture of the above-mentioned fullerenes or a mixture of a fullerene and a fullerene derivative may be used. Fullerenes generally have low solubility in organic solvents, but for example, Proceedings Op.
Malereals Research Society (Proceed
ings of Research Societ
y), Vol. 584, pp. 103-114, liquid mask material 20 is prepared by using a single solvent or a mixed solvent composed of xylene, dichlorobenzene or the like for C60 or C70. As shown in FIG. 1 or 2, the second resist film 3 can be spin coated.

That is, by using the fullerene solution, the liquid mask material 20 can be attached to the overhang-shaped hole pattern 10 (FIGS. 1 and 2). Here, the fullerene solution is a xylene solution which is a mixture of xylene and fullerenes C60 and C70, which will be described later in the first and second embodiments.

If the liquid mask material 20 can be attached, as shown in FIGS. 1 and 2, even if the film thickness of the mask material 20 becomes uneven, the dot pattern size of the mask material 20 is The first lower layer of the overhang-like hole pattern (consisting of the first resist film 2 and the second resist film 3)
It is determined by the opening size of the resist film 2. This allows
In the fine pattern forming method of the present invention, in the mask material attaching step of attaching the mask material 20, there is no dimensional variation as in the case of the conventional vapor phase mask attaching method, and High-precision substrate processing with high in-plane uniformity is possible.

Further, since the mask material 20 is attached by spin coating at a normal temperature process, overhang-like holes formed by the first resist film 2 and the second resist film 3 at the time of attachment like the conventional example. The pattern 10 is not thermally deformed. Further, fullerene is known to be sensitive to high-energy rays 4 such as ultraviolet rays and electron beams used in this process and cause intermolecular bonding reaction.

For example, Thin Solid Films (T
Hin Solid Films), Volume 257, Volume 1
85-203 (1995),
In the film composed of C60 molecules, the molecules are bound to each other by irradiation with ultraviolet rays. As a result, the fullerene film becomes a stronger mask due to the above-mentioned intermolecular bonds,
The etching resistance in anisotropic etching during patterning is amplified, and the accuracy of substrate processing for the substrate 1 to be processed is improved.

Further, since fullerenes are pure carbon materials and react with oxygen to form carbon dioxide gas, if fullerenes are used as the mask material 20, the substrate 1 to be processed is subjected to plasma treatment of oxygen gas after substrate processing. The mask material 20 can be completely removed without damage. As a result, the fine pattern forming method of the present invention can realize highly reliable substrate processing.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> A first embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a cross-sectional view of a device for explaining the first embodiment of the fine pattern forming process of the present invention. It is a figure. As shown in FIG. 1A, the first resist film 1 is spin-coated on the surface of the substrate 1 to be processed. Then, the solvent contained in the first resist film 2 is removed and a heat treatment for solidifying the resist is performed to form the first resist film 2 on the surface of the substrate 1 to be processed.

Next, the second resist film 3 is spin-coated on the surface of the first resist film 2. Then, the solvent contained in the second resist film 3 is removed and heat treatment is performed to solidify the resist, and the first resist film 2 is formed on the surface of the substrate 1 to be processed.
Then, a two-layer resist film including the second resist film 3 is formed. In the first embodiment, silicon carbide (SiC) is used for the substrate 1 to be processed, and in each resist film, a positive electron beam resist (ZEP520 manufactured by Nippon Zeon Co., Ltd.) is used as the first resist film 2. As resist film 3, fullerene composite ZEP520 described in Japanese Patent Application No. 09-149744 (ZE of the positive type electron beam resist described above is used.
A fullerene content of 20 wt% in P520 was used.

In the process of FIG. 1A, the thicknesses of the first resist film 2 and the second resist film 3 are 100 nm and 50 nm, respectively. In addition, the first resist film 2
The sensitivity difference between the second resist film 3 and the second resist film 3 is about 1.5.
(Ie, (sensitivity of fullerene composite ZEP520 of second resist film 3 in upper layer): (sensitivity of ZEP520 of first resist in lower layer) ≈1: 1.5).

Next, as shown in FIG. 1B, the first
The regions corresponding to the pattern are irradiated with the high-energy ray 4 on the resist film 2 and the second resist film 3, and the irradiated regions are removed by the developing process. As a result, similarly to the conventional example, the overhang-shaped hole pattern 10 composed of the first resist film 2 and the second resist film 3 is formed. In the first embodiment, the accelerating voltage 10 is used as the irradiation means of the high energy rays 4.
An electron beam exposure device of 0 kV was used.

Then, as described above, a resist film having a two-layer structure composed of the first resist film 2 and the second resist film 3 is drawn by the high energy rays 4, and then the first resist film 2 and the first resist film 2 are formed. The resist film 3 of No. 2 is developed for 60 seconds by a developing solution for ZEP520. As a result, as shown in FIG. 1B, the overhang-shaped hole patterns 10 arranged at a pitch of 60 nm are formed. In the first embodiment, fullerene composite ZEP5 having a fullerene content of 20 wt% is used.
Although 20 was used as the upper layer resist (second resist film 3), the fullerene content rate can be freely changed according to the target dot pattern.
It is possible to optimize the shape of the.

Next, as shown in FIG. 1C, a liquid mask material 20 is formed on the overhang-shaped hole pattern 10.
(Xylene solution at this point) is spin-coated, and the mask material 20 is attached to the surfaces of the substrate 1 to be processed and the second resist film 3 (since it is the upper layer resist) exposed without the resist. In the first embodiment, fullerene C
A xylene solution of a mixture of 60 and C70 (mixing ratio about 4: 1) is spin coated. Then, after the spin coating of the xylene solution, heat treatment was performed to remove xylene from the xylene solution to form a mask material 20 which was a fullerene mixture film.

At this time, the fullerene mixture remains in the pattern opening (the opening of the hole pattern 10) of the upper second resist film 3 by adjusting the concentration of the fullerene mixture in the xylene solution and the coating rotation speed. It is possible to spin coat the xylene solution so that it does not. The mixing ratio of fullerenes C60 and C70 in the xylene solution was adjusted so that the film thickness of the fullerene mixture after the heat treatment in the opening of the lower first resist film 2 (opening of the hole pattern 10) was about 80 nm. .

Next, as shown in FIG. 1D, the substrate 1 to which the mask material 20 which is a fullerene mixture is attached is dipped in a resist stripping solution to form a first resist film 2 and a second resist film 3. Is removed to remove the mask material 20 which is a fullerene mixture on the surface of the second resist film 2. As a result, a dot pattern made of the mask material 20 which is a fullerene mixture is formed on the surface of the substrate 1 to be processed. Here, a commercially available stripping solution (N-methyl-
2-Pyrrolidone) was used to immerse the entire substrate 1 to be processed, whereby each resist film was peeled off. In the stripping process using the stripping solution, the stripping process can be accelerated by using ultrasonic waves.

Next, as shown in FIG. 1 (e), the substrate 1 to be processed is processed by dry etching using the dot pattern formed by the mask material 20 as a mask. In the first embodiment, the substrate 1 to be processed, which is a SiC substrate, is etched by dry etching using a gas containing a halogen element to form a SiC dot-shaped pattern array 25 having a pitch of 60 nm.

Next, as shown in FIG. 1F, after the dry etching, the mask material 20 is separated from the substrate 1. In the first embodiment, the mask material 2
Since the fullerene that is a carbon material is used for the mask material 0, the mask material 20 that is a fullerene mixture can be easily removed by a general-purpose oxygen plasma processing apparatus.

At this time, the mask material 2 made of fullerene
For the mask removal process of 0, if there is no concern of substrate damage to the substrate 1 to be processed, it is also possible to use a removal solution composed of sulfuric acid and hydrogen peroxide, and the mask removal process of the mask material 20 can be performed. It will be easier. Further, in the first embodiment, the two-layer resist that can surely execute the lift-off process has been described as an example, but the present invention is also applicable to a single-layer resist using only the first resist film 2.

<Second Embodiment> Next, a second embodiment of the present invention will be described. FIG. 2 is a cross-sectional view of a device for explaining a second embodiment of the fine pattern formation process of the present invention. As shown in FIG. 2A, as in the first embodiment, the first resist film 2 is formed on the surface of the substrate 1 to be processed.
Spin coating. Then, the solvent contained in the first resist film 2 is removed and a heat treatment for solidifying the resist is performed to form the first resist film 2 on the surface of the substrate 1 to be processed.

Next, the second resist film 3 is spin-coated on the surface of the first resist film 2. Then, the solvent contained in the second resist film 3 is removed, and a heat treatment for solidifying the resist is performed.
The resist film 2 is formed. In the second embodiment, silicon carbide (SiC) is used for the substrate 1 to be processed, and a positive electron beam resist (ZEP520 manufactured by Nippon Zeon Co., Ltd.) is used as the first resist film 2 in each resist film.
As the second resist film 3, fullerene composite ZEP520 described in Japanese Patent Application No. 09-149744 (fullerene content of 20 wt% in ZEP520 of the positive electron beam resist) was used.

In the process of FIG. 2A, the thickness of the first resist film 2 and the second resist film 3 are 100 nm and 50 nm, respectively. The sensitivity difference between the first resist film 2 and the second resist film 3 was about 1.5 times (that is, (sensitivity of fullerene composite ZEP520 of upper second resist film 3): (Sensitivity of ZEP520 of the lower first resist film 2) ≈1: 1.5).

Next, as shown in FIG. 2B, the first
Areas corresponding to the pattern to be formed are irradiated with the high-energy rays 4 on the resist film 2 and the second resist film 3, and the irradiated areas are removed by the developing process. As a result, similarly to the first embodiment, the overhang-shaped hole pattern 10 including the first resist film 2 and the second resist film 3 is formed. In the second embodiment, an electron beam exposure apparatus with an accelerating voltage of 100 kV was used as the irradiation means of the high energy beam 4.

Then, as described above, after drawing a resist film having a two-layer structure consisting of the first resist film 2 and the second resist film 3 by a high energy river, the first resist film 2 and the second resist film 2 are formed. The resist film 3 is developed with a ZEP520-dedicated developer for 60 seconds. As a result, as shown in FIG. 1B, the overhang-shaped hole patterns 10 arranged at a pitch of 60 nm are formed. In the second embodiment, fullerene composite ZEP5 having a fullerene content of 20 wt% is used.
Although 20 was used as the upper layer resist (second resist film 3), the fullerene content rate can be freely changed according to the target dot pattern.
It is possible to optimize the shape of the.

Next, as shown in FIG. 2C, a liquid mask material 20 is formed on the overhang-shaped hole pattern 10.
(Xylene solution at this point) is spin-coated, and the mask material 20 is attached to the surfaces of the substrate 1 to be processed and the second resist film 3 (since it is the upper layer resist) exposed without the resist. In the second embodiment, fullerene C
A xylene solution of a mixture of 60 and C70 (mixing ratio about 4: 1) is spin coated. Then, after the spin coating of the xylene solution, heat treatment was performed to remove the xylene from the xylene solution to form a mask material 20 which was a fullerene mixture film.

At this time, the fullerene mixture remains in the pattern opening (the opening of the hole pattern 10) of the upper second resist film 3 by adjusting the concentration of the fullerene mixture in the xylene solution and the coating rotation speed. It is possible to spin coat the xylene solution so that it does not. The mixing ratio of fullerene C60 and C70 in the xylene solution is adjusted so that the film thickness of the fullerene mixture film after the heat treatment in the opening of the lower first resist film 2 (opening of the hole pattern 10) becomes about 80 nm. It was adjusted.

Next, as shown in FIG. 2 (c), the surface of the substrate 1 to be processed is collectively irradiated with high energy rays 6 (for example, ultraviolet rays). In the second embodiment, the high-energy rays 6 are irradiated with ultraviolet rays having a wavelength of around 300 nm, but ultraviolet rays in other wavelength regions or electron beams can also be used. Also, for ultraviolet rays with a wavelength of 300 nm or less,
Since the ZEP520 resist used in this embodiment causes a molecular cleavage reaction, it has an advantage of facilitating lift-off because dissolution by a stripping solution is promoted in the following lift-off process.

Next, as shown in FIG. 2 (d), the substrate 1 to which the mask material 20 which is a fullerene mixture is attached is dipped in a resist stripping solution to form a first resist film 2 and a second resist film.
The resist film 3 is removed to remove the mask material 20 which is a fullerene mixture adhering to the surface of the second resist film 2. As a result, a dot pattern made of the mask material 20 of the fullerene mixture is formed on the surface of the substrate 1 to be processed. Here, a commercially available stripping solution (N-
Methyl-2-pyrrolidone) was used to immerse the entire substrate 1 to be processed, whereby each resist film was peeled off. In the stripping process using the stripping solution, the stripping process can be accelerated by using ultrasonic waves.

Next, as shown in FIG. 2E, the target substrate 1 is processed by dry etching using the dot pattern formed by the mask material 20 as a mask. In the second embodiment, the substrate 1 to be processed, which is a SiC substrate, was etched by dry etching using a gas containing a halogen element to form a SiC dot-shaped pattern array 25 having a pitch of 60 nm.

Next, as shown in FIG. 2F, after the dry etching, the mask material 20 is removed from the substrate 1 to be processed. In the second embodiment, the mask material 2
Since the fullerene that is a carbon material is used for the mask material 0, the mask material 20 that is a fullerene mixture can be easily removed by a general-purpose oxygen plasma processing apparatus.

At this time, the mask material 2 made of fullerene
For the mask removal process of 0, if there is no concern of substrate damage to the substrate 1 to be processed, it is also possible to use a removal solution composed of sulfuric acid and hydrogen peroxide, and the mask removal process of the mask material 20 can be performed. It will be easier. Further, in the second embodiment, a two-layer resist that can surely execute the lift-off process has been described as an example, but a single-layer resist using only the first resist film 2 is also applicable.

The first and second embodiments of the present invention have been described above in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment and does not depart from the gist of the present invention. Even if the design of the range is changed, it is included in the present invention.

[0047]

As described above, according to the present invention,
Since a dense mask material made of a highly resistant carbon material can be obtained, highly precise nanometer-level fine pattern formation can be realized. Further, according to the present invention, a carbon material (for example,
A mask material made of fullerene or a fullerene derivative) has no contamination on device performance and can be easily peeled off by oxygen plasma treatment, and thus has high process compatibility and practicality.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a device for explaining a fine pattern forming method according to a first embodiment of the present invention as seen from a line.

FIG. 2 is a cross-sectional view of a device illustrating a fine pattern forming method according to a second embodiment of the present invention.

FIG. 3 is a line sectional view of a device for explaining a fine pattern forming method according to a conventional example.

[Explanation of symbols]

1 ... Substrate 2 ... First resist film 3 ... second resist film 4,6 ... High energy rays 20 ... Mask material

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Claims (4)

[Claims] 1. A fine pattern formation for forming a pattern made of the mask material on the substrate by depositing a mask material on the pattern formed on the resist film on the substrate and then removing the resist film. In the method, a fine pattern forming method, wherein the mask material is fine particles having aggregates of carbon atoms. 2. The fine pattern forming method according to claim 1, wherein the mask material is one or both of fullerene and a fullerene derivative. 3. The fine pattern forming method according to claim 1, further comprising a step of depositing the mask material by a spin coating method. 4. The fine pattern forming method according to claim 1, further comprising an irradiation step using a high energy ray after the mask material attaching step.