JP3170940B2 - Method of forming fine pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the patterning of a resist layer, and more particularly to a method for forming a fine pattern.

[0002]

2. Description of the Related Art In recent years, as high-density and high-speed large-scale integrated circuits (LSIs) have been required to miniaturize elements, the wavelength of light used in a photolithography process in the manufacturing process is short. A finer element can be formed. X-ray exposure is expected as a next-generation microfabrication technology replacing optical lithography.

A conventional method of forming a fine pattern in X-ray exposure is performed as follows. That is, as shown in FIG. 4, a material layer 12 to be processed is formed on a semiconductor substrate 11, and an X-ray resist layer 13 is formed on the material layer 12 to be processed. Next, an X-ray 16 is exposed by an exposure apparatus using an X-ray mask.
Exposes a desired fine pattern (FIG. 7A), and further develops to form a resist pattern (FIG. 7B).
Figure). Next, the material to be processed 12 is patterned by performing an etching process or the like using the resist pattern as a mask.

[0004]

However, according to the conventional method, even if a fine pattern of 0.15 μm or less is formed by X-ray exposure, when the thickness of the resist layer 13 becomes 1.0 μm or more, the height of the pattern width is reduced. Aspect ratio 6.5
As described above, in the step of removing the developing solution during the development, an excessive force is applied to the resist pattern, and the resist pattern collapses. As shown in FIG. 5, when the resist film is 1.0 μm in thickness, the typical pattern of the resist pattern is broken at a height of about 0.2 μm. This is considered to be because a force exceeding the elasticity of the resist is mainly applied to the resist head during development. Due to the fall of the resist, a serious problem is caused in a subsequent etching process and the like, and a problem occurs that a desired pattern cannot be formed.

The present invention has been made to solve the above problems.
An object of the present invention is to provide a method for forming a fine pattern in which a fine resist pattern does not collapse during development.

[0006]

In order to solve the above-mentioned problems, a method for forming a fine pattern according to the present invention comprises forming a resist layer on a material to be processed, and irradiating a desired region where the fine pattern is to be formed with ultraviolet light or a remote light. By irradiating ultraviolet rays,
A layer hardly soluble in a developing solution is formed on the surface layer of the resist layer, and then a desired fine pattern is exposed to X-rays, followed by development. Since the head of the resist is supported by the hardly-solubilized layer, it is possible to prevent the resist from falling down.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1A to 1E are cross-sectional views schematically showing a method of forming a fine pattern according to a first embodiment of the present invention in the order of steps.

First, a material layer 12 to be processed is formed on a semiconductor substrate 11.
To form Next, a film thickness of 1.0 μm is formed on the material layer 12 to be processed.
m negative type X-ray resist 13 is applied ((a)
Figure). Next, by irradiating a KrF excimer laser beam 14 to a region where a fine pattern of 0.15 μm or less is to be finally formed via a photomask 17, a surface layer portion of the KrF excimer laser exposed portion of the X-ray resist layer 13 is irradiated.
A layer hardly soluble in a developer having a depth of 0.2 μm (hereinafter referred to as a surface hardly soluble layer 15) is formed (FIG. 2B). Next, as in the case of the conventional method, a desired LSI pattern including a fine pattern of 0.15 μm or less is exposed by the X-ray 16 through the X-ray mask 18 (FIG. 10C), and development processing is performed. By the development process, 0.15
A fine pattern of μm or less is formed (FIG. 4D). The surface hardly-solubilized layer 15 has a structure for supporting the fine pattern from falling down from above, and this structure prevents the resist pattern from falling even at a high aspect ratio. Then, by removing the surface insoluble layer 15 by dry etching or the like, a desired fine resist pattern with a high aspect ratio can be obtained ((e)).
Figure).

FIGS. 2A to 2E are cross-sectional views schematically showing a method of forming a fine pattern according to a second embodiment of the present invention in the order of steps.

First, a material layer 1 to be processed is formed on a semiconductor substrate 11.
Form 2 Next, a film thickness of 1.0
A μm negative X-ray resist 21 is applied. further,
0.2 μm-thick negative type KrF on the X-ray resist layer 21
An excimer laser resist 22 is applied. Next, K
By irradiating the region where a fine pattern of 0.15 μm or less is finally desired to be formed through the photomask 17 with the rF excimer laser beam 14, the exposed portion of the resist layer for the negative type KrF excimer laser has a thickness of 0.2 μm. A layer hardly soluble in the liquid (hereinafter referred to as a hardly soluble layer 23) and a soluble layer are formed in the unexposed portions. Then, in the same manner as in the case of the conventional method, 0.
A desired LSI pattern including a fine pattern of 15 μm or less is exposed and developed. By the development process, a fine pattern of 0.15 μm or less is formed below the hardly-solubilized layer 23. The hardly-solubilized layer 23 has a structure for supporting the fine pattern from falling down from above, and this structure prevents the resist pattern from falling even at a high aspect ratio. Next, by removing the hardly-solubilized layer 23 by dry etching or the like, a desired fine resist pattern having a high aspect ratio can be obtained.

FIGS. 3A to 3E are cross-sectional views schematically showing a fine pattern forming method according to a third embodiment of the present invention in the order of steps.

First, a material layer 1 to be processed is formed on a semiconductor substrate 11.
Form 2 Next, a film thickness of 1.0
A μm positive X-ray resist 21 is applied. further,
0.2 μm thick positive type KrF on the X-ray resist layer 21
An excimer laser resist 22 is applied. Next, K
By irradiating the region where a fine pattern of not more than 0.15 μm is desired to be finally formed with the rF excimer laser beam 14 through the photomask 17, the hardly-solubilized layer 23 is formed in the unexposed portion of the positive type KrF excimer laser resist layer. A soluble layer is formed in the exposed area. Next, as in the case of the conventional method, 0.15 μm
A desired LSI pattern including a fine pattern of m or less is exposed and developed. By the developing treatment, the hardly soluble layer 23
A fine pattern of 0.15 μm or less is formed in the lower part of the substrate. The hardly-solubilized layer 23 has a structure for supporting the fine pattern from falling down from above, and this structure prevents the resist pattern from falling even at a high aspect ratio. Then, by removing the hardly-solubilized layer 23 by dry etching or the like, a desired fine resist pattern with a high aspect ratio can be obtained.

The difference between the second embodiment and the third embodiment is that X
This depends on whether each resist is negative or positive for the line and the KrF excimer laser.

In the above embodiment, a KrF excimer laser is used to form a hardly-solubilized layer on the surface of the X-ray resist. However, depending on the absorption coefficient of the resist, an ArF excimer laser, g-ray or i-line may be used. A light source such as a line may be used.

[0016]

As described above, according to the present invention, a resist layer is formed on a material to be processed, and a desired region in which a fine pattern is to be formed is irradiated with ultraviolet rays or far ultraviolet rays, whereby the surface layer of the resist layer is formed. After forming a layer insoluble in the developing solution in the portion, and then exposing a desired fine pattern by X-rays, by performing a development process, the head of the resist is supported by the insoluble layer, the resist generated during development Falling can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional configuration view of a method for forming a fine pattern according to a first embodiment of the present invention.

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

FIG. 3 is a cross-sectional configuration diagram of a fine pattern forming method according to a third embodiment of the present invention.

FIG. 4 is a cross-sectional configuration diagram of a conventional method for forming a fine pattern.

FIG. 5 is a view showing a typical manner of falling of a resist.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Semiconductor substrate 12 Material to be processed 13 X-ray resist layer 14 KrF excimer laser 15 Surface insoluble layer 16 X-ray 17 Photomask 18 X-ray mask 21 X-ray resist layer 22 Resist layer for KrF excimer laser 23 Insoluble layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/027 G03F 7/26 511 G03F 7/38 511

Claims (2)

(57) [Claims] 1. A step of forming a first resist layer sensitive to X-rays on a semiconductor substrate, and forming a second resist layer sensitive to ultraviolet light or far ultraviolet light on the first resist layer. Forming a layer hardly soluble in a developing solution and a layer soluble in a developing solution in a predetermined region of the second resist layer by exposing to ultraviolet light or far ultraviolet light through a photomask; A method for forming a fine pattern, comprising: a step of exposing to X-rays through a line mask; and a step of developing the first resist layer and the second resist layer. 2. The fine pattern according to claim 1, wherein the hardly-solubilized layer is removed by a dry process.
The method of formation.