JPH05291130A - Multilayer resist method and manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent pattern deterioration clue to diffusion of catalyst material into lower layer resist, by containing catalyst generating agent in the composition of a part where the lower layer resist comes into contact with an upper layer resist, which agent generates the same kind of catalyst as the catalyst used in the latent image forming reaction in relation to the development of chemical amplification system resist. CONSTITUTION:Composition composed of the following is dissolved; 80wt.% of crezol novolak resin, 15wt.% of heat crosslinking agent of 3-substituted ester of trihydroxybenzophenone and o-naphthoquinone diazidesulfonic acid, and 5wt.% of acid generating agent of triphenyl-sulfonium trifluoromethanesulfonate A coating film is formed from the above solution by a spin-coating method, and turned into first lower layer resist 3. Chemical amplification system resist which contains silicon is dissolved, and an upper resist layer 2 is formed by spin-coating. Writing is performed by electron beam irradiation. At this time, an acid catalyst generating part 8 which compensates diffusion of acid catalyst is formed just under a latent image 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device for forming a pattern by applying a multi-layer resist method to deep ultraviolet lithography or electron beam lithography using a KrF excimer laser (248 nm) as a light source. The present invention relates to a multi-layer resist method in which a chemically amplified silicon-containing resist exhibiting high sensitivity to these radiation sources is used to simplify the process, and a semiconductor device manufacturing method using the multi-layer resist method.

[0002]

2. Description of the Related Art Conventionally, a photosensitive resin material and a photoresist used in photolithography are used as a coating film formed on a substrate to be etched, and the coating film is irradiated with a predetermined pattern of light. The pattern-shaped latent image is formed in the coating film and developed to obtain a resist image having a predetermined pattern. The photolithography is to form a predetermined pattern on a substrate to be etched by an etching process using the resist image as a mask.

In recent years, in such a single-layer resist method, the step difference of the substrate becomes a size that cannot be ignored with respect to the processing dimension, and the variation in the resist film thickness caused by the step difference affects the resolution. That is, the pattern irradiation light and the reflected light from the substrate form a standing wave in the resist film, which affects the latent image in the resist, but if the resist film thickness changes due to the substrate step, The effect on image quality is also large. Further, since the optimum developing time also depends on the resist film thickness, the resolution performance is further influenced by the presence / absence of a substrate step.

One of means for solving such a problem is
In a method called a multi-layer resist method, a typical method is a lower layer resist made of an organic resin having a high resistance to the etching process on a substrate to be etched, a relatively thin intermediate layer made of a coatable glass, and the like, and This is called a three-layer resist method using three layers of an upper layer resist that forms a predetermined pattern image by pattern exposure such as ultraviolet rays. In a multi-layer resist method such as a three-layer resist method,
A substrate having a step is also flattened by the lower resist.
Therefore, this lower layer resist is also called a flattening layer. The intermediate layer formed on the flattening layer is pattern-transferred by etching using the upper layer resist on which a predetermined pattern image is formed as a mask. Subsequently, using this intermediate layer pattern as a mask, oxygen reactive ion etching (O ₂ RIE) is performed.
The pattern transfer is performed on the lower flattening layer made of an organic resin by the above method.

According to this method, the lower planarizing layer can be sufficiently stabilized by a thermal crosslinking reaction or the like before the pattern is formed, so that it can have sufficient resistance to dry etching of various substrates, and thus can be used for general purpose. Since the reactive ion etching having high property and directional property can be used for the etching process used for transferring the pattern to the lower layer resist, the formed lower layer resist pattern has a high aspect ratio. Also,
The upper layer imaging resist can also be formed on the already flattened substrate, and in general, the organic polymer type resist has a large resistance to the fluorine plasma used for the glassy etching of the intermediate layer and is used in a relatively thin film. Therefore, it is advantageous in resolution performance as compared with lithography using a single-layer resist.

However, the multi-layer resist method is complicated in its process and is disadvantageous in industrial use. In order to compensate for this, a method using a silicon-containing resist having a large O ₂ RIE resistance has been developed as the upper layer resist. Regarding a silicon-containing resist that can be used in such a two-layer resist method, U.S. Pat. No. 4,689,288, 4,
722,881 etc.

On the other hand, recently, a lithography light source has been widely used in order to improve the optical resolution.
The g-line (436 nm) and i- which are the emission lines of a high pressure mercury lamp
Far-ultraviolet lithography using a KrF excimer laser (248 nm) or the like, which is a radiation source having a wavelength shorter than that of a line (365 nm), electron beam lithography, X-ray lithography, and the like are under study. Various chemically amplified resists have been developed that are advantageous for these sources in terms of sensitivity, resolution, exposure profile, etc. JP-A-2-173647, JP-A-2-
As described in JP-A No. 129642 and Japanese Patent Application Laid-Open No. 2-105156, a silicon-containing chemically amplified resist aiming at application to a two-layer resist method has also been developed.

[0008] The chemically amplified resist is a resist that utilizes a pattern-like exposure to generate a catalytic substance and induce a pattern forming reaction related to development by a reaction using the catalytic substance as a catalyst. Therefore, as compared with the conventional resist that directly induces the latent image formation reaction related to development by the pattern-like exposure, a slight catalyst generated by the exposure is used for the latent image formation reaction, so that the sensitivity is effectively high. ..

However, when this is used in the multilayer resist method as an upper layer imaging resist, a slight amount of catalyst generated by exposure diffuses to the lower layer resist in contact therewith, thereby lowering the catalyst concentration at the interface portion and causing a latent image forming reaction. Becomes insufficient and the development pattern deteriorates. Regarding such a phenomenon that appears when a chemically amplified resist is applied to a three-layer resist process and its countermeasure, Japanese Patent Laid-Open No. 14163/1993
2 and JP-A-2-290012. However, in the two-layer resist method using a silicon-containing chemically amplified resist, the lower layer in contact with the upper imaging resist is an organic resin layer, and the method described in the known example cannot be used.

[0010]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to transfer a pattern in which a silicon-containing chemically amplified resist is used as an upper layer imaging resist to a lower layer resist made of an organic resin by oxygen reactive ion etching. An object of the present invention is to prevent the pattern deterioration due to the diffusion to the lower layer of the exposure generation catalyst, which is a problem in the resist method, and realize an industrially advantageous multilayer resist method.

[0011]

The above problems are solved by using an upper layer resist pattern formed using a silicon-containing chemically amplified resist as a mask, and using this pattern as a lower layer resist made of an organic resin using a dry etching medium containing oxygen plasma. In the multi-layer resist method of transferring to a layer, a catalyst of the same kind as the catalyst used in the latent image forming reaction relating to the development of the chemically amplified resist is generated in the composition of at least a portion of the lower layer resist in contact with the upper layer resist. It is achieved by a multi-layer resist method characterized by containing a catalyst generator.

Silicon-containing chemically amplified resists usable in the present invention are disclosed in JP-A-2-173647 and JP-A-2-129642.
No. 2, JP-A-2-105156, a silicone resin which produces a catalytic substance such as an acid by irradiation with active actinic radiation and forms a latent image for development by a catalytic reaction along the catalytic substance producing portion. A pattern forming composition using

The catalyst generator contained in the composition of at least the portion of the lower layer resist of the present invention which comes into contact with the upper layer resist generates a catalyst of the same kind as the catalyst used in the latent image forming reaction involved in the development of the upper layer resist. If the catalyst generator, for example, the catalyst is an acidic substance, the same acidic substance may be used. However, it is more suitable if it produces the same catalyst.

Since the lower resist layer is the resist pattern itself of the dry etching process of the semiconductor substrate, it is desirable that the lower resist layer is crosslinked and insolubilized by heat treatment or the like.
Furthermore, when the upper layer resist is applied, it must already be insoluble in the application solvent. Therefore, the catalyst generator contained in the lower layer resist is desired to have sufficient resistance to the insolubilization treatment of the lower layer resist. In this respect, when utilizing the insolubilization of the lower layer resist by the heat treatment, for the chemical amplification system utilizing the acid-catalyzed reaction,
An onium salt having a large heat resistance was suitable. However, the present invention is characterized in that a catalyst for compensating a catalytic reaction that forms a latent image related to the development of the upper layer resist is generated in the lower layer resist portion which contacts the upper layer resist along the pattern exposure. The catalyst generator is not limited to onium salts.

[0015]

[Function] With the upper layer resist pattern formed by using the silicon-containing chemically amplified resist, the upper layer resist pattern is transferred to the lower layer resist layer made of an organic resin by using the dry etching medium containing oxygen plasma as a mask. The catalyst substance generated along the latent image produces a concentration gradient in the vicinity of the interface with the lower resist layer. Therefore, when the lower resist layer is an organic resin layer similar to the matrix resin of the upper resist, the diffusion of the generated catalyst substance into the lower resist layer depending on the concentration gradient is unavoidable, which is accompanied by the development of the upper resist. The related pattern latent image formation reaction becomes insufficient near this interface,
A good upper layer resist pattern could not be obtained.

In the present invention, in the composition of at least the portion of the lower layer resist that contacts the upper layer resist, a catalyst generator that generates the same kind of catalyst as the catalyst used in the latent image forming reaction relating to the development of the chemically amplified resist is used. Since it contains, in the pattern-wise exposure to the upper layer resist, even in the portion in contact with the upper layer resist of the lower layer resist which is inevitably exposed,
The same kind of catalytic substance as that used in the pattern latent image forming reaction involved in the development of the upper resist is produced. The catalyst substance generated in the lower layer resist compensates for the catalyst substance that is lost along with the diffusion of the catalyst substance generated along the latent image in the upper layer resist to the lower layer resist layer. The fact that the latent image forming reaction related to development is insufficient at the interface with the lower layer resist is greatly reduced.
Alternatively, it can be avoided.

[0017]

【Example】

<Example 1> An example in which the present invention is applied to a process of processing a wiring layer of a silicon semiconductor device using an electron beam drawing technique will be described with reference to FIG.

After forming an aluminum film 5 having a thickness of 0.7 μm to be a wiring layer on a silicon semiconductor substrate 6, a radiation-induced conductive lower layer resist material RE-3960B (Hitachi Chemical Co., Ltd. product) is applied at 180 ° C. After baking for 5 minutes, a second lower resist layer 4 having a thickness of 1.6 μm was formed.

On top of that, cresol novolac resin: 8
A composition comprising 0 parts by weight, 15 parts by weight of a trisubstituted ester of trihydroxybenzophenone and o-naphthoquinonediazide sulfonic acid as a thermal crosslinking agent, and 5 parts by weight of triphenylsulfonium trifluoromethane sulfonate as an acid generator, A coating film is formed by a spin coating method from a solution dissolved in 2-ethoxyethyl acetate at a concentration of about 7 wt.%, And further baked at 180 ° C for 10 minutes to a thickness of 0.1.
First lower resist layer 3 containing 5 μm acid generator
And

Next, as a silicon-containing chemically amplified resist, alkali-soluble silicon resin polyhydroxybenzylsilsesquioxane: 90 parts by weight, diphenylsilanediol: 10 parts by weight, triphenylsulfonium trifluoromethanesulfonate: 8 A coating film is formed by a spin coating method from a solution prepared by dissolving a composition of 1 part by weight in a solid concentration of about 20 wt.% In 2-ethoxyethyl acetate, and further baked at 80 ° C. for 10 minutes to a thickness of 0.3 μm.
m 2 as the upper resist layer 2.

As the active actinic rays 1, an electron beam drawing apparatus having an accelerating voltage of 30 kV was used to draw an electron beam in a predetermined wiring pattern at a dose of 2 microcoulombs / cm ² . Immediately below the latent image 7 consisting of the acid catalyst generation portion formed along the electron beam exposed portion in the upper layer resist, an acid catalyst generation portion 8 for compensating the diffusion of the acid catalyst in the upper layer resist by the same exposure is formed. It

Then, the semiconductor substrate is baked at 90 ° C. for 10 minutes to accelerate the latent image formation reaction associated with the development according to the pattern shape, and a tetramethylammonium hydroxide aqueous solution (concentration 1.4 wt%) is used as the developing solution. As the above, the upper resist layer 2 was developed to obtain a development pattern 9. The second and first lower resist layers 4 using the development pattern 9 as an etching mask.
Was subjected to etching treatment by reactive ion etching of oxygen to obtain a lower layer resist pattern 10 used for processing the wiring layer 5. When the aluminum wiring layer 5 was dry-etched using this resist pattern as an etching mask, a fine wiring pattern 11 having a good aspect ratio could be formed.

<Embodiment 2> A wavelength of 248 is used instead of the electron beam.
A wiring layer of a silicon semiconductor device was processed using the same process as in Example 1 except that the deep ultraviolet exposure technique using a KrF excimer laser light source of nm was used, and a fine wiring pattern with a good aspect ratio was obtained. Could be formed. At this time, the exposure amount of far ultraviolet rays was 5 millijoules / cm ² .

<Embodiment 3> As the active actinic radiation in Embodiment 1, a pattern having a line width of 0.5 μm or less is drawn by using an electron beam, and a pattern having a line width larger than that is used in Embodiment 2.
Other processes except that the exposure was performed by using the KrF excimer laser stepper used in Example 1, and the aluminum wiring layer was processed into a semiconductor substrate in the same manner as in Example 1. A wiring pattern with a wide aspect ratio could be formed.

[0025]

According to the present invention, a method of manufacturing a semiconductor device in which deep ultraviolet rays such as an electron beam or an excimer laser light source is used as a radiation source and a pattern is formed by applying a multi-layer resist method, and the method is high in these radiation sources. Using a chemically amplified silicon-containing resist that exhibits sensitivity, a multilayer resist method that simplifies the process and a method of manufacturing a semiconductor device using the multilayer resist method, which is a problem in a method of exposing a catalyst material to an underlayer resist generated by exposure Since the deterioration of the pattern due to the diffusion can be prevented, the fine processing of the highly integrated semiconductor device can be realized with high accuracy and high efficiency.

[Brief description of drawings]

FIG. 1 is an explanatory view of a process using an electron beam drawing technique for latent image formation by applying a multilayer resist method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Actinic actinic radiation, 2 ... Upper resist layer consisting of silicon-containing chemically amplified resist, 3 ... First lower resist layer containing acid generator, 4 ... Second lower resist layer consisting of organic resin, 5 ... Wiring metal layer, 6 ... Semiconductor substrate, 7 ... Compensation catalyst generating part, 8 ... Latent image forming part, 9 ... Development pattern, 10 ...
Lower layer resist pattern.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fumio Murai 1-280 Higashi Koikeku, Kokubunji, Tokyo Inside Central Research Laboratory, Hitachi, Ltd. (72) Hidenori Yamaguchi 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi Ltd. Central Research Laboratory (72) Inventor Toshio Sakamizu 1-280 Higashi Koikekubo, Kokubunji, Tokyo Inside Hitachi Central Research Laboratory

Claims (4)

[Claims] 1. A multi-layer resist in which the upper layer resist pattern formed using a silicon-containing chemically amplified resist is used as a mask to transfer the upper layer resist pattern to a lower layer resist layer made of an organic resin by using a dry etching medium containing oxygen plasma. In the method, the composition of at least a portion of the lower resist layer in contact with the upper resist contains a catalyst generator that generates the same catalyst as the catalyst used in the latent image forming reaction involved in the development of the chemically amplified resist. A multi-layer resist method characterized by: 2. The catalyst according to claim 1, wherein the catalyst used in the latent image forming reaction involved in the development of the chemically amplified resist is an acidic substance, and the catalyst generator contained in the lower layer resist is an acid generator. Is a multi-layer resist method. 3. A method of manufacturing a semiconductor device according to claim 2, including a step of processing a predetermined film structure on a semiconductor substrate into a pattern shape by a lithography process, and including at least one lithography process. 4. The method of manufacturing a semiconductor device according to claim 3, wherein the application process of the multilayer resist method is a wiring layer processing process.