JPH05304086A - Pattern forming method - Google Patents

Abstract

PURPOSE:To form a resist pattern excellent in shape by a method wherein an exposed part and an unexposed part is made clear in contrast at silylation. CONSTITUTION:A resist 2 is formed on a substrate 1 and exposed to light using a mask of required pattern, far-ultraviolet rays are made to irradiate the resist 2 to form an Si-containing monomolecular layer on the pattern-exposed part of the resist 2, and then the resist 2 is selectively developed by etching for the formation of a resist pattern. Contrast between the exposed part and the unexposed part is made clear at sililation, a pattern of excellent shape can be formed, and consequently a device can be manufactured high in yield.

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 in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art Conventionally, as a method for forming a fine pattern, silylation of a resist (formation of a monomolecular layer containing Si) and O _{2 for} forming a high resolution pattern using only the surface of a resist.
A method by etching has been proposed. (For example,
F. Coopmans et al., Proc. Of SPIE, vol.631, p.34 (19
86)) However, in this method, there is a problem that the pattern shape is deteriorated because the unexposed portion is silylated.

An example of the above-mentioned conventional pattern forming method will be described below with reference to the drawings.

FIG. 2 is a process sectional view of a conventional pattern forming method. A resist (PLASMASK301-U made by Nippon Synthetic Rubber) 2 is applied and formed on the substrate 1 by 1.5 μm (FIG. 2 (a)). Exposure 4 is performed using a KrF excimer laser stepper (NA 0.42) through the mask 3 (FIG. 2B). Then, heating 8 at 180 ° C. for 60 seconds is performed (FIG. 2 (c)). Then, the vapor 6 of hexamethyldisilazane is heated at 180 ° C. for 90 seconds to perform silylation treatment on the exposed portion (FIG. 2 (d)). O ₂ RI
The unexposed portion is removed at E to form a pattern 2C (FIG. 2E). However, since the unexposed portion 2D was also silylated, the 2D could not be completely removed by O ₂ RIE, and the pattern was deteriorated. Such a deteriorated pattern leads to a defect in a later process and eventually causes a reduction in the yield of the device.

[0005]

The above-mentioned structure has a problem that a defective pattern causes a reduction in the yield of semiconductor devices.

[0006]

That is, the pattern forming method of the present invention comprises a step of irradiating the entire surface with far-ultraviolet light before silylation, instead of the step of heating after pattern exposure.

In view of the above problems, the present invention provides a fine pattern forming method which prevents silylation of a resist unexposed area and makes the best use of the characteristics of the silylation method. That is, the present invention comprises a step of forming a resist on a substrate,
Pattern exposing using a desired mask, irradiating the resist with far-ultraviolet light having lower energy than the pattern exposing, and exposing the resist pattern exposed portion to a monomolecular layer containing Si (silylation ) Is formed, and the resist is selectively developed by dry etching to form a resist pattern.

[0008]

According to the present invention, since the far ultraviolet light cross-links the unexposed portion of the resist pattern-exposed by the above-mentioned constitution,
The reaction of the silylation to the unexposed area is prevented, and only the exposed area is silylated, so that a fine pattern having a good shape can be formed by O ₂ etching. The influence of crosslinking on the exposed portion of the pattern exposure by far ultraviolet light can be ignored because the energy of the pattern exposure is higher. That is, although the non-exposed portion was conventionally cross-linked by heating, the present inventors have found that far-ultraviolet light has a higher efficiency of cross-linking and that the exposed portion is not cross-linked. It was

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pattern forming method according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a pattern forming method in an embodiment of the present invention. On a substrate 1 such as a semiconductor,
Resist (for example, PLASMASK3 made by Japan Synthetic Rubber)
01-U) 2 is formed by coating 1.5 μm (FIG. 1).
(A)). Exposure 4 is performed using a KrF excimer laser stepper (NA 0.42) through the mask 3 (see FIG. 1).
(B)). After that, ArF light 5 is applied to the entire surface at 10 mJ / cm ² (FIG. 1C). Then, the vapor 6 of hexamethyldisilazane is heated at 180 ° C. for 90 seconds to silylate the exposed portion (FIG. 1 (d)). That is, in this step, the exposed portion of the resist 2 is silylated to form a monomolecular layer containing Si. Unexposed area 2 by O ₂ RIE
B is removed to form pattern 2A (see FIG. 1).
(E)). In the above method, since the unexposed portion 2B of the resist 2 was not crosslinked by the cross-linking of the unexposed portion 2B with the ArF light 5, the dry development was performed so that only the pattern 2A remained completely selectively by O ₂ RIE. Was done. As a result, the pattern 2A was a 0.25 μm pattern having a good shape without any pattern connection. Examples of the far-ultraviolet light include light from a mercury lamp or ArF laser light. Examples of the silylation method include coating and vapor deposition. As the silylation material, disilazane,
Trisilazane compounds may be mentioned.

[0011]

As described above, according to the present invention, a pattern having a good shape can be formed by irradiating far-ultraviolet light before silylation instead of heating, which leads to an improvement in device yield.

[Brief description of drawings]

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

FIG. 2 is a process sectional view of a conventional pattern forming method.

[Explanation of symbols]

 1 substrate 2 resist 3 mask 4 KrF excimer laser light 5 ArF light 6 hexamethyldisilazane vapor 7 heating 8 heating 2A, 2C patterns 2B, 2D unexposed area

Claims (4)

[Claims] 1. A step of forming a resist on a substrate, a step of performing pattern exposure using a desired mask, a step of irradiating the resist with far-ultraviolet light over the entire surface, and a pattern-exposed portion of the resist containing Si. A method for forming a pattern, comprising: a step of forming a monomolecular layer containing: and a step of selectively developing the resist by dry etching to form a resist pattern. 2. The pattern forming method according to claim 1, wherein the far-ultraviolet light is light from a mercury lamp or ArF laser light. 3. The pattern forming method according to claim 1, wherein the method for forming the monomolecular layer is coating or vapor deposition. 4. The pattern forming method according to claim 1, wherein the material forming the monomolecular layer containing Si is a disilazane or trisilazane compound.