JPH08234451A - Pattern forming method - Google Patents

Abstract

PURPOSE: To make it possible to relatively easily form various kinds of micropatterns even if intricate method are not used by forming desired patterns, then processing these patterns with a processing liquid which brings about volumetric expansion. CONSTITUTION: A resist 2 is formed on a substrate 1 to be worked. Next, this resist 2 is subjected to ordinary lithography, by which the desired parts of the resist are selectively removed and the desired patterns 3 are formed. The processing liquid 4 of a dimethyl aminomethyl silane sol. subjected to temp. control is then dropped on the patterns 3 and the patterns are processed in this state. The processing liquid 4 is then removed. The volume of the patterns 3 formed in such a manner are expanded. Namely, the desired patterns 3 are formed on the resist film on, for example, the substrate 1 to be worked, and are exposed to at least liquid contg. dye or silylating agent contg. a silicon element, thereby, the dye or the silylating agent is diffused into the resist patterns. The increase in material density is thereby induced in the resist patterns and the volume of the resist patterns occurring in the increase in the density is expanded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic technique in ULSI manufacturing or the like, and more particularly to a method of forming a resist pattern for processing an underlying substrate to be processed with a single layer resist.

[0002]

2. Description of the Related Art High integration of LSI has been achieved by being supported by a lithography technique which is a means for forming a fine pattern. This lithography technique includes a technique of using light as an exposure source for pattern formation, a technique of using an electron beam, a technique of using an X-ray and an ion beam. Among them, photolithography using light is excellent in mass productivity. Therefore, it has been used for mass production technology of memory LSI such as DRAM. However, the recent high degree of integration of LSI requires a fine dimension equal to or smaller than the wavelength of light used for mass production so far, which results in a half-micron dimension or less. It has become increasingly difficult to perform such fine processing by photolithography.

In photolithography, various measures have been taken to improve fine workability. One of the methods is a technique for improving the optical image itself of a fine pattern by using the phase information of light, and it has been confirmed that a dimension pattern of about half the wavelength of exposure light can be processed. However, there are many restrictions, such as the effect of improving the resolution using the phase information of light, depending on the type of the pattern, and the hole pattern is said to have such a small effect that it is difficult to process.

Therefore, as a method of improving the fine workability of the hole pattern, investigations are being made from the viewpoint of the lithography process. Recently, Proceedings of the 54th Annual Meeting of the Japan Society of Applied Physics, p. 548 "Examination of micro slit pattern formation using undersize of pattern dimension by resin coating" and 41st Proceedings of the Joint Lecture on Applied Physics After forming a desired pattern on the first resist layer, as described in p.568, "Study on formation of minute hole pattern using undersize of pattern dimension by resin coating", or Japanese Patent Laid-Open No. 5-166717. ,
A method of applying a second mixing-prone material again and forming a mixing layer in which the first resist and the second material are mixed on the pattern forming wall surface to reduce the pattern size is considered. ing.

However, it has been confirmed that the mixing layer formed as described above changes the cross-sectional shape of the pattern before and after the use of the above method, and in particular, the cross-sectional shape of the hole pattern is changed from the vertical cross-sectional shape in order. It is shown to change to a tapered shape. When the forward taper pattern is used as described above, the dimension shift amount of the transfer pattern becomes large during the subsequent dry etching of the base substrate, which makes it difficult to secure desired fine workability. Problems or even in-plane distribution of pattern dimensions,
Problems such as increased dimensional variation tend to occur. When the above problems occur, it becomes difficult to achieve stable lithography.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of miniaturizing a pattern, which solves the problem of the forward taper shape of the resist pattern sidewall portion of the prior art as described above.

[0007]

The method of forming a fine pattern by miniaturizing the pattern size of the present invention solves the above-mentioned problem of the forward taper shape by expanding the volume of the formed pattern. For example, a desired pattern is formed on a resist film on a substrate to be processed, and then the dye or the silylating agent is diffused into the resist pattern by exposing at least a liquid containing the pigment or a silylating agent containing a silicon element. As a result, the material density of the resist pattern is increased, and the volume of the resist pattern is expanded due to the increase of the density, thereby miniaturizing the opening portion of the resist pattern. When the volume expansion is generated only near the surface of the resist pattern, it is easier to control the variation in the volume expansion amount depending on the density of the pattern. Of course, other materials that expand the volume of the resist can be used instead of the dye and the silylating agent.

A method of controlling the volume expansion amount can be achieved by controlling the processing time of the volume expansion processing liquid, but the desired pattern formation resist solvent and a non-polar solvent such as xylene are used. By treating with the mixed solution, it is possible to modify only the vicinity of the resist surface so as to selectively enter the dye or the silylating agent without damaging the resist pattern shape. Further, the thickness of the modified portion can be controlled by reducing the concentration of the resist solvent in the mixed solution.

On the other hand, SPII Vol. 1262 Advances in Resist Technology VII (SPIE Vol. 1262 Advances in Resist Techno
logyand Processing VII (1990)) has shown that the thickness of silylated part changes with the irradiation of light. Therefore, by irradiating the resist material with far-ultraviolet light having a large light absorption after forming a desired pattern, as in the case of controlling the thickness of the modified portion by the mixed solution, only the extreme surface of the resist pattern is selectively modified. By qualifying, a desired volume expansion with high controllability can be obtained.

Further, during the volume expansion treatment with the dye or the silylating agent, at the same time as or after the volume expansion treatment, heat at room temperature or higher is applied, or the processing atmosphere itself or the processing liquid itself is maintained at room temperature or higher. In addition, the volume expansion smoothly proceeds, and the pattern can be miniaturized and the processing time can be shortened.

[0011]

Since the dye or the silylating agent diffuses from the resist surface to a uniform depth according to a constant diffusion constant, the pattern can be miniaturized while maintaining the vertical sectional shape of the pattern.

[0012]

【Example】

<Embodiment 1> An embodiment of the present invention will be described with reference to FIG.
FIG. 1 is an explanatory view of a series of processing steps of the present invention. FIG.
As shown in (a), a resist 2 is formed on the substrate 1 to be processed. Here, a novolac-based positive type resist having a novolac resin as a base resin, in which a portion irradiated with energy rays is removed by an alkali developing treatment, is used.
As shown in FIG. 1B, a desired portion of the resist 2 was selectively removed by performing ordinary lithography to form a desired pattern 3.

Then, as shown in FIG. 1 (c), the treatment liquid 4 of the dimethylaminomethylsilane solution whose temperature is adjusted to 40 ° C. for the pattern 2 is dropped, and the treatment liquid is treated for 2 minutes in this state, and then the treatment liquid 4 was removed. As a result of evaluating the pattern processed as described above using an electron beam microscope, it was confirmed that the pattern size can be reduced by about 0.05 μm as compared with the pattern size formed by only ordinary lithography. Even when the treatment liquid 4 was vaporized and treated for 5 minutes in a reduced pressure gas phase atmosphere whose temperature was adjusted to 100 ° C., a similar pattern miniaturization effect was obtained.

When the treatment with the treatment liquid 4 is carried out after the pretreatment with the xylene solution containing 10% of ethyl cellosolve acetate for 2 minutes, the pattern size is 0.07 μm, which is an effect of miniaturization of the pattern as compared with the case shown above. Has increased. It is considered that this is because an organic solvent of cellosolve acetic acid such as ethyl cellosolve acetate is used as a coating solvent for a resist material capable of alkali development and the film quality of the resist is relaxed by the action of the organic solvent. As an alternative to ethyl cellosolve acetate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, acetic acid-n-
Organic solvents of cellosolve acetic acid such as propyl, N-methyl-2-pyrrolidone and n-butyl alcohol can also be used.

The above treatment is not limited to cellosolve acetic acid as long as the material has a function of relaxing the film quality of the resist.
Further, the pretreatment can be simplified by using a mixed solution obtained by mixing xylene containing ethyl cellosolve acetate with dimethylaminomethylsilane.

Further, the treatment liquid 4 is replaced with a xylene solution containing 2% of an anthracene dye belonging to a polynuclear aromatic compound,
It was found that the pattern could be miniaturized when treated with the solution containing anthracene for 10 minutes, though not as much as the dimethylaminomethylsilane solution. Similarly, when the treatment liquid 4 was treated with o-anisidine belonging to aromatic amine for 10 minutes, a pattern miniaturization effect similar to that of anthracene was obtained. Further, when the treatment liquid 4 was treated with a solution of cyclohexylamine belonging to an aliphatic amine for 10 minutes, the same pattern of miniaturization was observed.

<Second Embodiment> Next, a second embodiment will be described with reference to FIG. First, as shown in (a), a desired pattern 23 was formed by ordinary lithography. Thereafter, as shown in (b), far ultraviolet light 27 having an exposure wavelength of 219 nm, which is highly absorbed by the resist 22, was applied to the entire surface of the resist pattern for 30 seconds. Then, as shown in (c), a gas phase atmosphere of dimethylaminomethylsilane 24 was applied for 2 minutes. As a result, as in Example 1, volume expansion 25 occurred in the resist, and pattern miniaturization 26 could be achieved. It was also confirmed that the density of the pattern and the variation in volume expansion due to the pattern size are small.

On the other hand, the resist 2 or 2 shown in the embodiment
No. 2 is not limited to a positive novolak-based resist, and may be a negative type or an isopropylene-based, epoxy-based, polystyrene-based, or acrylate-based resist material other than the novolak-based resist. After the pattern formation, if the desired volume expansion can be obtained by diffusing a substance such as a dye, the present method can be used. Further, as the dye, a dye similar to the anthracene described in this example, or other dyes such as acryl din orange and acryl din yellow can be used. Hexamethyldisilane, hexamethylcyclotrisilazane, dimethylaminomethylsilane and the like can be used as the silylating agent.

[0019]

According to the present invention, various patterns can be relatively easily miniaturized even by a conventional lithography method without using a complicated method such as a method of improving an optical image. Since the concept of the present invention lies in further miniaturizing a pattern formed by ordinary lithography, it can be used not only for photolithography but also for lithography such as electron beam or X-ray as a method for forming a fine pattern. Therefore, it is possible to strongly promote the lithography technology that requires finer patterns, and to further develop high integration and high performance of semiconductor elements such as ULSI and ultrafine devices.

[Brief description of drawings]

FIG. 1 is a sectional view of a pattern forming method according to an embodiment of the present invention.

FIG. 2 is a sectional view of a pattern forming method according to a second embodiment of the present invention.

[Explanation of symbols]

1 ... Substrate to be processed, 2 ... Resist, 3 ... Pattern forming part,
4 ... Processing atmosphere, 5 ... Area where resist film thickness is increased by volume expansion, 6 ... Miniaturized pattern forming portion.

Claims (12)

[Claims] 1. A desired pattern is formed by a step of forming a resist layer which is exposed to an energy ray on a substrate to be processed, and irradiating the desired area with the energy ray, and a step of at least developing the resist layer. In the pattern forming method, after the desired pattern is formed, it is treated with a treatment liquid that causes volume expansion. 2. A desired pattern is formed by the steps of forming a resist layer which is exposed to energy rays on a substrate to be processed, and irradiating the desired area with the energy rays, and at least developing the resist layer. In the pattern forming method, after forming the desired pattern, a step of treating with a treating solution for relaxing the film quality of the resist pattern, a step of treating with a treating solution for causing volume expansion, or a treating solution and a volume for causing the film quality change. A pattern forming method comprising performing a treatment with a mixed liquid with a treatment liquid that causes expansion. 3. The pattern forming method according to claim 1, wherein the volume expansion is limited to the vicinity of the surface of the resist on which the desired pattern is formed. 4. The pattern forming method according to claim 1, wherein the volume expansion is limited to the surface, and the diffusion of the processing liquid causing the volume expansion is controlled. 5. The pattern forming method according to claim 4, wherein the diffusion is controlled only by using a treatment liquid that reduces the quality of the resist film. 6. The pattern formation method according to claim 4, wherein the diffusion is controlled by irradiating the resist film with light having a large surface absorption to the desired pattern. 7. The pattern expansion method according to claim 1, 2 or 3, wherein the volume expansion of the resist pattern is performed in a liquid phase or a gas phase. 8. The volume expansion of the resist pattern according to claim 1, 2, or 3 is a pattern formation caused by at least a part of components constituting a processing liquid being diffused and accumulated in the resist pattern. Method. 9. A pattern forming method, wherein a silylating agent is used in the processing solution for volume expansion of the resist pattern according to claim 1, 2, or 3. 10. The pattern forming method according to claim 1, wherein the resist pattern treatment liquid is a treatment liquid containing an aromatic amine or an aliphatic amine. 11. A pattern forming method, wherein the resist pattern treatment liquid according to claim 1, 2, or 3 is a treatment liquid containing a dye of a polynuclear aromatic compound. 12. A pattern forming method using an organic solvent containing cellosolve acetic acid as a treatment liquid for relaxing the film quality of the resist pattern according to claim 2 or 5.