JPH04243263A - Fine pattern forming method - Google Patents

Abstract

PURPOSE:To conduct the etching being strong in the selectivity by performing the oxidation treatment on the sililated portion of the resist for dry development use by using preliminary ultraviolet ray and ozone. CONSTITUTION:The resist 3 for dry development use is applied on a substrate 1 and the exposed portion 3a is sililated and subsequently is dry-developed. The sililated portion 5 of the resist 3 is preliminary carried out the oxidation treatment Namely while the resist 3 for dry development use is exposed to an ozone gas, the ozone gas is irradiated with light. Like this at the etching time with the reactive ions, when the oxygen ions having energy are irradiated, a stable oxidized film 30 against the oxygen ions has already been formed on the sililated portion 5. Then compared to the case that the oxygen ions are irradiated from the beginning, the etching of the sililated portion is hard to proceed.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD The present invention relates generally to a method for forming fine patterns, and more specifically to DE.
This invention relates to improvements in a method for forming fine patterns using the SIRE process.

0002

[Prior art] DESIRE (diffusion e)
enhanced silylating resist
) process was described by Coopmans and Rol in 1986.
This is a dry development resist process announced by and. Figure 3 is from Monthly Semiconductor
World 1988 No. 8 is a cross-sectional view of the conventional DESIRE process introduced in No. 8.

Referring to FIG. 3(a), a dry development resist 3 for the DESIRE process is applied onto a film 2 formed on a substrate 1. The dry development resist 3 is mainly composed of novolac resin, for example, P.
LASMASK (registered trademark of Japan Synthetic Rubber Co., Ltd.). Using the mask 4 on the dry development resist 3,
Light with a wavelength of 365 to 436 nm is selectively irradiated using a stepper or the like. Thereby, referring to FIG. 3(b), the dry development resist 3 is divided into an exposed area 3a and an unexposed area 3b.

Referring to FIG. 3(c), the dry development resist 3 in the exposed area is silylated. The silylation process is
This is carried out by introducing the substrate 1 into a vacuum chamber and spraying a silane coupling agent containing Si atoms, such as HMDS (hexamethyldisilazane) gas, onto the resist surface while raising the temperature of the substrate 1. HMDS has a chemical structure as shown in FIG. 4, and selectively diffuses only into the exposed areas 3a of the dry development resist 3, causing silylation. In the dry development resist 3, HMDS gas and
The novolak resin, which is the main component of the dry development resist 3, reacts as shown in FIG. 5, and as a result, the resin 5 containing Si is formed only in the exposed areas 3a.

Referring to FIG. 3(d), when the substrate 1 is introduced into a reactive ion etching apparatus and subjected to reactive ion etching using O2 gas, the resin 5 into which Si atoms have been introduced is first exposed to O2 plasma. and changes into a SiO2 layer 6.

Referring to FIG. 3(e), etching does not progress under the SiO2 layer 6, while etching progresses in the unexposed portion 3b. As a result, a negative resist pattern 40 is formed on the substrate 1. This DESI
The RE process has the characteristics of high resolution, low sensitivity to reflection from the substrate, and high heat resistance.

[0007]

[Problem to be solved by the invention] By the way, DESIR
The important processes in the E process are shown in Figure 3 (d
) to (e) are dry etching steps. In the step shown in FIG. 3(e), in order to obtain a resist shape perpendicular to the substrate 1, O2 ions having a certain level of energy and directionality are irradiated vertically toward the substrate 1. It is necessary to do so.

However, with reference to FIGS. 3(c) and 3(d), when O2 ions with energy above a certain level are irradiated toward the substrate 1, an etching-resistant SiO2 layer 6 is formed. Previously, there was a problem in that etching of the resin 5 containing Si atoms progressed and sufficient etching selectivity could not be obtained.

The present invention was developed to solve the above-mentioned problems, and provides a method for forming fine patterns using the DESIRE process, which is improved so that sufficient etching selectivity can be obtained. The purpose is to

0010

[Means for Solving the Problems] The present invention includes a step of applying a dry development resist onto a substrate, a step of selectively exposing the dry development resist, and a step of exposing the exposed portion of the dry development resist to light. The present invention relates to a method for forming a fine pattern using the DESIRE process, which includes a step of silylation, and a step of dry developing the dry development resist after the silylation. In order to solve the above problem, the silylated portion of the resist for dry development is previously subjected to oxidation treatment prior to the dry development.

According to a preferred embodiment of the present invention, the oxidation treatment is carried out by exposing the silylated dry developing resist to ozone gas and irradiating the ozone gas with light.

0012

[Operation] According to the present invention, when energetic O2 ions are irradiated during reactive ion etching, an oxide film that is stable against O2 ions is already formed on the silylated portion. . Therefore, compared to when irradiating with O2 ions from the beginning, etching of the silylated portion becomes more difficult to proceed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing a method for forming a fine pattern according to an embodiment of the present invention.

The steps related to FIGS. 1(a) to 1(c) are shown in FIG.
This is the same as the steps related to a) to (c), and corresponding parts are given the same reference numerals and their explanations will not be repeated.

Referring to FIGS. 1(c) and 1(d), after the silylation of the exposed area is completed, the silylated resin 5 is oxidized. Oxidation treatment is performed using ultraviolet light and ozone.

FIG. 2 is a schematic diagram of the oxidation treatment apparatus. Referring to FIG. 2, the oxidation processing apparatus includes a vacuum chamber 11. A vacuum pump 12 is connected to the vacuum chamber 11 . An ozone generator 18 is connected to the vacuum chamber 11 for feeding ozone gas into the chamber. A pipe line 21 for introducing O2 gas is connected to the ozone generator 18, and the O2 gas introduced from the pipe line 21 is changed into O3 gas by the ozone generator 18. The generated O3 gas is transferred to the ozone gas pipe 22.
It is configured to be sent into the vacuum chamber 11 through the. The vacuum chamber 11 is provided with a window 13 made of quartz glass so that ultraviolet rays 15 irradiated from a mercury lamp 14 can enter the vacuum chamber 11 . A heating means 16 for heating the substrate 1 is provided within the vacuum chamber 11 .

Next, the operation of the oxidation treatment will be explained. A substrate 1 provided with a silylated dry development resist 3 shown in FIG. 1(c) is placed on a heating means 16 provided in a vacuum chamber 11. The substrate 1 is heated by heating means 1
6 (can be heated to several tens to hundreds of degrees Celsius),
Heat. Ozone gas produced by an ozone generator 18 is introduced into the vacuum chamber 11 . On the other hand, the vacuum pump 12 is driven, and the inside of the vacuum chamber 11 is heated to several to several tens of mmT.
Exhaust to orr. The mercury lamp 14 is turned on and ultraviolet rays 15 are introduced into the vacuum chamber 11. By this operation, the silylated resin 5 is oxidized and an oxide film 30 is formed on the surface, as shown in FIG. 1(e).

Referring to FIG. 1(f), the oxidized substrate 1 is introduced into a reactive ion etching apparatus and subjected to reactive ion etching. According to the embodiment, when energetic O2 ions are irradiated during reactive ion etching, the oxide film 30, which is stable against O2 ions, has already been formed on the silylated portion, so Etching of the silylated portion becomes more difficult than when irradiating with O2 ions, and as a result, highly selective etching becomes possible.

In the above embodiments, the oxidation treatment is performed using ozone gas and ultraviolet rays, but the present invention is not limited to this, and as long as the resin containing Si atoms is oxidized, Either can be used.

[0020] Further, in the above example, the case where HMDS gas is used as the silylating agent is illustrated, but the present invention is not limited thereto. Any organometallic gas can be used.

[0021]

Effects of the Invention As explained above, according to the present invention, during reactive ion etching, energetic O2
When ions are irradiated, an oxide film that is stable against O2 ions has already been formed on the silylated parts, so the etching of the silylated parts is faster than when irradiated with O2 ions from the beginning. As a result, highly selective etching becomes possible. As a result, a dry development resist pattern with good resolution and pattern shape can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a method for forming a fine pattern according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram of an oxidation treatment apparatus used in the present invention.

FIG. 3 is a cross-sectional view showing a conventional DESIRE process.

FIG. 4 is a diagram of the chemical structure of hexamethyldisilazane used in the DESIRE process.

FIG. 5 is a diagram showing a silylation reaction in the DESIRE process.

[Explanation of symbols]

1 Board 2. Membrane 3 Resist for dry development 4 Photomask 3a Exposure section 3b Unexposed area 5　Silylated resin 30 Oxide film

Claims (1)

[Claims] 1. A step of applying a resist for dry development on a substrate, a step of selectively exposing the resist for dry development, a step of silylating the exposed portion of the resist for dry development, and a step of silylating the exposed portion of the resist for dry development; DESI comprising the step of dry developing the dry development resist after dry development.
In a method of forming a fine pattern by RE process,
A method for forming a fine pattern, characterized in that, prior to the dry development, the silylated portion of the dry development resist is previously oxidized.