JPH04264557A - Formation of fine pattern - Google Patents

Abstract

PURPOSE:To enable silylation to be conducted at room temp. and to form good fine patterns by silylating a resist by using a silylating agent contg. imidazole to be a catalyst for silylation or its deriv. CONSTITUTION:The polyimide resist 2 to form a lower layer resist is applied on a semiconductor substrate 1 and thereafter, a novolak resist 3 to form an upper layer resist is applied thereon. The upper layer resist 3 is then subjected to exposing and developing to form patterns and thereafter, the silylating agent 7 prepd. by incorporating the imidazole into, for example, chlorotrimethyl silane is sprayed at room temp. to form a silylated layer 9 on the surface of the upper layer resist 3. The fine patterns 10 are then formed by RIE etching using gaseous O2 plasma with the silylating layer 9 as a mask.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a semiconductor manufacturing process.
In particular, it relates to lithography processes.

0002

[Prior Art] As a conventional method for forming fine patterns, the silicon-added two-layer resist method is shown in FIG. 3(a).
) to (d).

First, as shown in FIG. 3A, a lower layer resist (eg, polyimide resist) 5 is coated on a semiconductor substrate 1, and an upper layer resist (eg, novolac resist) 6 is coated.

Next, as shown in FIG. 3(b), the upper resist 6 is exposed and developed to form a pattern.

Next, as shown in FIG. 3(c), by applying vapor of a silylating agent (such as hexamethyldisilazane or chlorotrimethylsilane) 8 while heating the entire resist, an upper resist 6 that can be silylated is formed. The surface of is silylated to form a silylated layer 9.

Next, as shown in FIG. 3(d), a fine pattern 10 is formed by dry etching by O2 RIE using the silylated layer 9 as a mask.

[0007] Usually, a resist based on novolac resin is used as the upper layer resist. As shown in chemical formula (1), the hydroxyl group contained in the molecular structure of the novolak resist of the upper layer resist, which is the first term on the left side, has the second term on the left side.
The silylating agent in the first term on the right side directly reacts and silylates, forming the silylated novolak resist in the first term on the right side.

[0008]

[0009]

[Problems to be Solved by the Invention] In order to improve the performance of resists, improvements such as the introduction of sidewalls to the molecular structure of novolac resins have been made, and the molecular structure of resist bases used for upper layer resists of submicron patterns, etc. has become complicated.

[0010] As a result, the three-dimensional structure becomes very complicated, and the hydroxyl group, which is the reactive part of the novolak resin, may be covered up, making it difficult to react. When a silyl group is directly introduced into a hydroxyl group contained in the molecular structure of a resist, silylation is quite difficult due to poor reactivity due to such steric hindrance.

[0011] In order to introduce silyl groups to the extent that sufficient resistance to RIE etching using O2 gas plasma is obtained, the reaction temperature must be set at a high temperature of 120-150°C or higher. However, when the silylation temperature becomes high, there is a problem in that the resist pattern flows and becomes deformed.

0012

[Means for Solving the Problems] The method for forming a fine pattern of the present invention includes a step of forming a resist film on one main surface of a semiconductor substrate and then exposing and developing it, and imidazole and an imidazole derivative serving as a silylation catalyst. and silylating the surface of the resist film using a silylating agent containing one of the above.

[0013]

[Operation] By incorporating imidazole or its derivative as a catalyst into the silylating agent, as shown in chemical formula (2), the imidazole in the second term on the left side bonds to the silylating agent in the first term on the left side, It becomes a highly reactive silylating agent, which is the first term on the right side. Next, as shown in chemical formula (3), the novolak resist in the first term on the left side combines with the highly reactive silylating agent in the second term on the left side, and the silylated novolac resist in the first term on the right side is formed. A system resist is formed.

[0014]

[0015]

[Example] Regarding the first example of the present invention, FIG. 1(a)
This will be explained with reference to (d).

First, as shown in FIG. 1A, a polyimide resist 2 serving as a lower resist layer is applied to a semiconductor substrate 1, and then a novolac resist 3 serving as an upper resist layer is applied.

Next, as shown in FIG. 1(b), the upper resist 3 is exposed and developed to form a pattern.

Next, as shown in FIG. 1(c), a silylating agent 7 containing imidazole in chlorotrimethylsilane, for example, is sprayed at room temperature to form the upper resist layer 3.
A silylated layer 9 is formed on the surface of the silylated layer 9.

Next, as shown in FIG. 1(d), RIE was performed using O2 gas plasma using the silylated layer 9 as a mask.
A fine pattern 10 is formed by etching.

Next, a second embodiment of the present invention will be explained with reference to FIGS. 2(a) to 2(d).

First, as shown in FIG. 2A, a novolac resist 3 serving as a lower layer resist is applied to a semiconductor substrate 1, and then a methacrylic resist 4 serving as an upper layer resist is applied.

Next, as shown in FIG. 2(b), the upper resist 4 is exposed and developed to form a pattern.

Next, as shown in FIG. 2C, a silylating agent 7 containing imidazole in chlorotrimethylsilane, for example, is sprayed at room temperature to form a silylated layer 9 on the exposed surface of the lower resist 3. form.

Next, as shown in FIG. 2(d), RIE was performed using O2 gas plasma using the silylated layer 9 as a mask.
The upper layer pattern 4 and the lower layer resist 3 are etched by a method to form an inverted fine pattern 10.

[0025]

Effects of the Invention In forming fine patterns, a resist is silylated using a silylating agent containing imidazole or a derivative thereof serving as a silylation catalyst. As a result, silylation became possible at room temperature and a good fine pattern could be formed.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention in order of steps.

FIG. 2 is a cross-sectional view showing a second embodiment of the present invention in order of steps.

FIG. 3 is a cross-sectional view showing a method for forming a fine pattern according to the prior art in order of steps;

[Explanation of symbols]

1 Semiconductor substrate 2 Polyimide resist 3 Novolac resist 4 Methacrylic resist 5 Lower layer resist 6 Upper layer resist 7 Imidazole-containing silylation agent 8
Silylating agent 9 Silylated layer 10 Formed fine pattern

Claims (1)

[Claims] 1. A step of forming a resist film on one main surface of a semiconductor substrate and then exposing and developing it, and using a silylation agent containing one of imidazole and an imidazole derivative as a catalyst for silylation. A method for forming a fine pattern, including a step of silylating the surface of a resist film.