JPH11231544A - Resist mask structure, method for accelerating sensitivity of chemically amplified resist and pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the sensitivity of a chemically amplified resist film. SOLUTION: This resist mask consists of a chemically amplified resist film 14 and a sensitivity accelerating film 12 to accelerate the sensitivity of the chemically amplified resist film by irradiation of radiation. The sensitivity accelerating film 12 is an acid producing film. In the resist mask structure, the acid producing film 12 consists of a film containing an acid producing agent and a resin having a SiO4-n (OR)n2 structure (wherein R represents alkyl groups, n is an integer satisfying 0<=4, and if n>=2, R may be same or different).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a resist mask structure, a method for promoting sensitivity of a chemically amplified resist, and a pattern forming method using a resist mask.

[0002]

2. Description of the Related Art In a process of manufacturing a semiconductor device, a silicon oxide film (SiO ₂ film) is used as an etching mask. When this silicon oxide film is used as an etching mask, first, a photoresist or an EB resist is applied on the silicon oxide film formed on the base. After that, for example, the EB resist is subjected to electron beam exposure to pattern the resist film to form a resist pattern as designed. In this case, since the resist material has a great influence on the throughput depending on the exposure amount, a highly sensitive resist is particularly required.

[0003] In recent years, chemically amplified resists have attracted attention as such resists.

As a conventional chemically amplified resist, for example, 3
Component resist (novolak + polyphthalaldehyde +
(Ph ₃ S) ⁺ (SbF ₆ ) ^- ) (Reference: Ultra LS)
Molecular design of I resist, Kyoritsu publisher, 1990, p.
p. 57-60).

[0005]

However, the conventional chemically amplified resist has not yet been sufficiently satisfactory in sensitivity of the chemically amplified resist in view of throughput.

Therefore, it has been desired to develop a resist mask structure, a method for promoting sensitivity of a chemically amplified resist, and a method for forming a pattern, which have a large throughput in semiconductor manufacturing.

[0007]

Therefore, according to the resist mask structure of the first invention, a chemically amplified resist film and a sensitivity enhancing film for promoting the sensitivity of the chemically amplified resist film due to irradiation with radiation. And characterized by the following. In practicing the present invention, preferably, the sensitivity promoting film is an acid generating film.

As described above, in the present invention, the resist mask structure is constituted by the chemically amplified resist film and the sensitivity promoting film. When radiation is applied to the sensitivity enhancing film, the sensitivity enhancing film enhances the sensitivity of the chemically amplified resist film due to the irradiation. Is promoted, and the sensitivity of the chemically amplified resist film is improved as compared with the related art. Further, when the sensitivity promoting film is an acid generating film, the acid generated from the sensitivity promoting film when the film is irradiated with radiation accelerates the chemical reaction of the chemically amplified resist film to increase the sensitivity of the film. It can be more reliably improved. The chemically amplified resist film and the sensitivity enhancing film may be in close contact with each other or may be separated from each other, but it is preferable that both are in close contact with each other.

In implementing the present invention,
Sets the acid generating film to SiO_4-n(OR) _n(However, R is al
And n represents an integer satisfying 0 ≦ n <4.
You. When n is 2 or more, R is the same or different.
May be. And) a film comprising a resin having a structure and an acid generator.
Good to do. Also, acid generator is triphenylsulfonate.
Um triflate (Ph_Three S⁺ OTf^-)
No.

With this configuration, since the acid generator contains an acid generator, an acid is generated from the acid generator at the time of radiation exposure, and the chemical reaction of the chemically amplified resist is prevented. It is thought to promote more.

In practicing the present invention, it is preferable that the chemically amplified resist film be a positive resist or a negative resist.

As described above, even if the chemically amplified resist film is a positive type or negative type resist film, the chemical reaction of the chemically amplified resist film can be promoted by the acid in the acid generating film by radiation exposure.

According to the method for promoting sensitivity of a chemically amplified resist according to the second invention, an acid generating film is provided in contact with the chemically amplified resist film, and the acid generating film is generated by irradiating radiation. The acid is used to enhance the sensitivity of the chemically amplified resist film to radiation.

With such a configuration, when the acid generating film is irradiated with radiation, an acid is generated from the acid generating film, and the acid is used to improve the sensitivity of the chemically amplified resist film to radiation. It is possible to do.

Further, according to the pattern forming method of the third invention, a step of forming a sensitivity enhancing film on the base and a step of forming a chemically amplified resist film by coating the chemically amplified resist on the sensitivity enhancing film. And performing a radiation exposure, a heat treatment, and a development process on the chemically amplified resist film and the sensitivity promoting film to form a resist mask. In practicing the present invention, preferably, the sensitivity promoting film is an acid generating film.

[0016] With this configuration, since the chemically amplified resist film is formed on the sensitivity promoting film, that is, the acid generating film, acid is generated from the sensitivity promoting film during the radiation exposure treatment. The acid promotes the chemical reaction of the chemically amplified resist film. For this reason, the sensitivity of the chemically amplified resist film is greatly improved as compared with the related art.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A resist mask structure, a sensitivity enhancement method and a pattern forming method according to an embodiment of the present invention will be described below with reference to the drawings. It should be noted that the drawings merely schematically show the size, shape, and arrangement relationship of each component to the extent that the present invention can be understood. Therefore, the present invention is not limited to the illustrated examples. Absent. Further, the materials used, the mixing ratio of the materials, and the process conditions described below are merely examples, and therefore, are not limited to these conditions.

In the present invention, the resist mask structure 19 includes the chemically amplified resist film 14 and the sensitivity promoting film 12 for promoting the sensitivity of the chemically amplified resist film 14.

Referring to FIG. 1, an embodiment of a resist mask structure according to the present invention will be described. FIG. 1 is a cross-sectional view illustrating a resist mask structure according to the present invention.

In this embodiment, a resist mask structure including a sensitivity promoting film 12 and a chemically amplified resist film 14 is formed on a base 10. The underlayer 10 includes a polysilicon (Si) film 102 on a silicon (Si) substrate 100.
And a silicon oxide (SiO ₂ ) film 104.

Here, the resist mask structure 19 is used.
An acid generating film is used as the sensitivity promoting film 12. This acid generating film 12 is made of SiO _4-n (OR) _n (where R represents an alkyl group, and n is an integer satisfying 0 ≦ n <4).
When n is 2 or more, R may be the same or different. A) A film composed of a resin having a structure and an acid generator. Here, poly (di-t-butoxylsiloxane) is used as the resin having the SiO _4-n structure, and triphenylsulfonium triflate is used as the acid generator.

For the formation of the chemically amplified resist film 14 used here, for example, a commercially available negative resist, SAL (trade name of Shipley) is used. In addition,
In this embodiment, as the chemically amplified resist film 14,
Although the negative resist material is used, a positive resist may be used instead of the negative resist.

As described above, since the acid generating film 12 is provided in contact with the chemically amplified resist film 14, the acid generated from the acid generating film 12 when the chemically amplified resist film 14 is exposed to radiation. (H ⁺ ) and chemically amplified resist film 1
4 is promoted, and the chemically amplified resist film 14 is formed.
Can be reduced. For this reason, the sensitivity of the chemically amplified resist is greatly improved (a comparison between the conventional exposure amount and the exposure amount of the present invention will be described later).

Next, with reference to FIGS. 2 to 6, an embodiment of a method for promoting sensitivity and a method for forming a pattern of a chemically amplified resist according to the present invention will be described. FIGS. 2, 3, 4, 5 and 6 are cross-sectional views for explaining the steps of the method for promoting sensitivity and the method for forming a pattern of the chemically amplified resist according to the present invention.

<First Embodiment> First, a sensitivity enhancement method according to a first embodiment of the present invention will be described with reference to FIGS. 2 (A), 2 (B) and 2 (C).

In the first embodiment, a coating solution used for forming the acid generating film 12 is prepared. This preparation method is as follows.

The resin used for the acid generating film 12 is poly (di-
t-butoxylsiloxane) (chemical formula below)
The acid generator is triphenylsulfonium triflate (the following chemical formula).

[0028] _{-SiO 3 (Ot-Bu) 1} - ····· Ph 3 S + OTf - ····· Here, poly (di -t- butoxylated siloxane) 18
0 g and triphenylsulfonium triflate 20 g
(10 wt%) and a solvent (methyl isobutyl ketone, 1
800 g). Then, the mixed solution was added for 0.2
The solution is filtered through a membrane filter having pores of μm to obtain a coating solution.

Next, this coating solution is spin-coated on the base 10 so that the film thickness is about 0.1 μm.

Thereafter, the structure including the coating film (not shown) is mounted on a hot plate (not shown), and a pre-baking process (for example, at 80 ° C. for about 1 minute) is performed to form the acid generating film 12. (FIG. 2A).

Next, a negative chemically amplified resist film 15 is coated on the acid generating film 12 so as to have a thickness of about 0.5 μm. At this time, as the negative-type chemically amplified resist film 15, for example, SAL (trade name of Shipley), which is a well-known material, is used. Thereafter, electron beam direct drawing (electron beam exposure) is performed using an electron beam as radiation to pattern the negative chemically amplified resist film 15 (FIG. 2B).

Next, the exposed structure is subjected to a predetermined heat treatment, for example, treatment at 120 ° C. for 1 minute, and then the negative chemically amplified resist film 15 is immersed in any suitable alkali developing solution. The resist other than the irradiated portion is removed to form a resist pattern 16 (FIG. 2C).

By using an alkali developing solution, the unexposed portion of the negative chemically amplified resist film 15 is removed, and the acid generating film 12 remains on the underlayer 10 as it is insoluble in the alkali developing solution. .

In the course of the above-mentioned steps, the acceleration voltage of the electron beam is set to 20 kV, and 0.1% at the time of electron beam exposure (EB exposure).
When the exposure amount for resolving the μm line was determined, 17 μC
/ Cm ² .

On the other hand, a commercially available SAL is used for the base 10
It was applied directly on the (oxide film) and the exposure amount for resolving a 1 μm line was found to be 27 μC / cm ² .

As described above, in the first embodiment,
Since the acid generating film 12 is provided between the base 10 and the negative type chemically amplified resist 15, the acid generating film 1
It is considered that an acid is generated from the acid generator contained in 2, and the acid promotes the chemical reaction of the negative chemically amplified resist film 15, resulting in a highly sensitive chemically amplified resist film.

<Second Embodiment> Next, a sensitivity enhancement method according to a second embodiment of the present invention will be described with reference to FIG.

The second embodiment differs from the first embodiment in that a positive resist is used as the chemically amplified resist film.

First, an acid generating film 12 is formed on a base 10 (FIG. 3A). As a coating film used for the acid generating film 12, a film similar to that of the above-described first embodiment is used.

Next, a positive chemically amplified resist film 18 is formed on the acid generating film 12. Here, the well-known resist 4, 4 is used as the positive chemically amplified resist film 18.
A resin containing 4'-bis (4-hydroxyphenyl) sulfone t-butoxycarbonyl and 4,4 '-(hexafluoroisopropylidene) diphenol t-butoxycarbonyl and an acid generator (triphenylsulfonium triflate) are used as a solvent. A resist coating solution dissolved in (cyclohexane) is used (Literature: Japanese Patent Application No. 7-147671).
issue).

Next, the positive chemically amplified resist film 18 is irradiated with ultraviolet rays (UL rays) as radiation (FIG. 3B). Here, the irradiation amount is, for example, 500 mJ.
/ Cm ² .

Next, the structure including the positive-type chemically amplified resist film 18 is carried into a heating furnace and subjected to a heat treatment at 100 ° C. for 10 minutes, for example. The heat treatment at this time is also called post-exposure bake. By performing such baking, the positive chemically amplified resist film 18 is substantially cured.

Thereafter, the structure shown in FIG. 3B is immersed in an alkali developing solution to remove the UL-irradiated portion to form a resist pattern 20 (FIG. 3C). Here, the alkali developer is, for example, tetramethylammonium hydroxide (sometimes referred to as TMAH). Further, the acid generating film 12 remains on the base 10 because it is insoluble in the alkali developing solution.

In the course of the process of the second embodiment, the acceleration voltage of the UL line used for the exposure is set to 20 kV, and the exposure amount for resolving the 0.1 μm line is calculated as 2.6 μC / cm ^2.
Met.

On the other hand, using a commercially available positive-type chemically amplified resist (SAL), an underlayer (here, an oxide film) 10
The exposure amount for resolving the 0.1 μm line when directly coated on the substrate was 3.1 μC / cm ² . Here, the acid generating film 12 is changed to an oxide film by the exposure and the post-exposure bake, so that, for example, there is no trouble in etching the base 10.

<Third Embodiment> Next, an embodiment of a pattern forming method using a resist mask according to the present invention will be described with reference to FIGS. The third
In the embodiment, an example in which a positive resist material is used as a chemically amplified resist film will be described.

In the third embodiment, the base 10 is
A structure in which a poly-Si film 102 and a silicon oxide film (SiO ₂ film) 104 are sequentially formed on a silicon substrate 100 is used. On the silicon oxide film 104, the same acid generating film 12 and the positive chemically amplified resist film 18 as in the second embodiment are formed. After that, the positive chemically amplified resist film 1
8 is exposed to ultraviolet light (FIG. 4A). Thereafter, the structure including the positive-type chemically amplified resist film 18 is carried into a heating furnace and subjected to a heat treatment at 100 ° C. for 10 minutes, for example.

Next, the structure of FIG. 4A is immersed in any suitable alkali developing solution to remove the exposed portion of the positive chemically amplified resist film 18 to form a resist pattern 20 (FIG. 4). (B)).

Thereafter, the acid generating film 12 and the SiO ₂ film 104 exposed on the lower surface of the groove 21 of the resist pattern 20 are etched by using, for example, a reactive ion etching method.

The etching conditions at this time are as follows.

Etching gas: CHF ₃ / CF ₄ rf Power: about 100 W Pressure: about 5 Pa Processing temperature: room temperature Under such etching conditions, the acid generating film 12 and SiO
_{2 The} film 104 is etched to form the acid generating film pattern 12a.
Then, an SiO ₂ film pattern 104a is formed (FIG. 5A).

Next, the structure shown in FIG. 5A is carried into a heating furnace (not shown) and heat-treated at about 400 ° C. for 10 minutes. Such a heat treatment is also referred to herein as baking. By such baking, the acid generating film pattern 1
2a is changed to an oxide film pattern 22 (FIG. 5B).

Next, oxide film patterns 22 and 104a
Is used as a mask to etch the poly-Si film 102 by, for example, a reactive ion etching method. The etching conditions at this time are as follows.

Etching gas: mixed gas of chlorine gas and oxygen gas (chlorine 1: oxygen 1) rf power: about 100 W pressure: about 5 Pa treatment temperature: room temperature Subsequently, the oxide film pattern 2 was formed using any suitable organic solvent.
2 and 104a are removed. Thus, the poly-Si film pattern 102a is formed on the Si substrate 100 (FIG. 5C).

<Fourth Embodiment> In a fourth embodiment, the acid generation film 12 and the SiO film 1 are formed by reactive ion etching using the resist pattern 20 as a mask.
The steps up to the step of etching 04 are performed in the same manner as in the third embodiment. Therefore, in this example, steps after the above-described step of FIG. 5A will be described. FIG. 5 (A)
6A is shown in FIG.

Next, the acid generating film pattern 12a is removed using, for example, any suitable solvent (FIG. 6B). Here, the solvent is anisole (methoxybenzene)
And

Next, using the oxide film pattern 104a as a mask, the poly-Si film 1 is formed by reactive ion etching.
02 is etched. The etching conditions at this time are as follows:
The etching conditions are the same as those in the third embodiment. Thus, the poly-Si film pattern 102a is formed on the Si substrate 100 (FIG. 6C).

The exposure amount of the 0.1 μm line of the chemically amplified resist films of the third and fourth embodiments was measured to be 2.6 μC / cm ² .

When the exposure amount of the present invention is compared with the conventional exposure amount, the exposure amount of the present invention is reduced by about 37% in the first embodiment compared with the conventional exposure amount. In the second to fourth embodiments, the exposure amount is reduced by about 16%.

In the above-mentioned embodiment, poly (di-t-butoxylsiloxane) is used as the resin. Instead of this poly (di-t-butoxylsiloxane), alkoxyl which can be eliminated by an acid is used. A poly (siloxane) derivative having a group may be used.

In this embodiment, an example in which an electron beam is used for exposure has been described.
An e-Hg lamp, i-line, g-line, X-ray, or ion beam may be used.

[0062]

As is apparent from the above description, according to the present invention, since the sensitivity enhancement film is used in contact with the chemically amplified resist film, the chemically amplified resist film is exposed to radiation. At this time, the chemical reaction between the acid generated from the sensitivity promoting film and the chemically amplified resist film is promoted, and the sensitivity of the chemically amplified resist film is substantially improved as compared with the related art.

Accordingly, since the throughput is improved as compared with the conventional case, the cost of the product can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view for explaining a resist mask structure of the present invention.

FIGS. 2A to 2C are cross-sectional views for explaining a sensitivity promoting method according to the first embodiment of the present invention.

FIGS. 3A to 3C are cross-sectional views illustrating a sensitivity enhancement method according to a second embodiment of the present invention.

FIGS. 4A and 4B are cross-sectional views for explaining a pattern forming method according to a third embodiment of the present invention.

FIGS. 5A to 5C are cross-sectional views illustrating a pattern forming method following FIG.

FIGS. 6A to 6C are cross-sectional views illustrating a pattern forming method according to a fourth embodiment of the present invention.

[Explanation of symbols]

 10: Underlayer 12: Acid generating film 14: Chemically amplified resist film 15: Negative type chemically amplified resist film 16: Resist pattern 18: Positive type chemically amplified resist film 19: Resist mask structure 20: Resist pattern 21: Groove 22: Oxide film Pattern 100: silicon substrate 102: polysilicon film 104: silicon oxide film

Claims (16)

[Claims] 1. A resist mask structure comprising a chemically amplified resist film and a sensitivity promoting film for promoting sensitivity of the chemically amplified resist film due to irradiation with radiation. 2. The resist mask structure according to claim 1, wherein said sensitivity promoting film is an acid generating film. 3. The resist mask structure according to claim 1, wherein said acid generating film is made of SiO _4-n (OR).
_n (where R represents an alkyl group, and n is 0 ≦ n <4
Is an integer that satisfies When n is 2 or more, R
May be the same or different. A) A resist mask structure characterized by being a film comprising a resin containing the structure and an acid generator. 4. The resist mask structure according to claim 1, wherein said chemically amplified resist film is a positive resist. 5. The resist mask structure according to claim 1, wherein said chemically amplified resist film is a negative resist. 6. An acid generating film is provided in contact with a chemically amplified resist film, and the sensitivity of the chemically amplified resist film to the radiation is promoted by an acid generated by irradiating the acid generating film with radiation. A method for promoting sensitivity of a chemically amplified resist, comprising: 7. A method according to claim 6, wherein said acid generating film is made of SiO _4-n (O
R) _n (where R represents an alkyl group, and n is 0 ≦ n)
<4. When n is 2 or more, R may be the same or different. A) A method for promoting sensitivity of a chemically amplified resist, which comprises forming a film comprising a resin having a structure and an acid generator. 8. The sensitivity of the chemically amplified resist according to claim 7, wherein the acid generator is triphenylsulfonium triflate (Ph ₃ S ⁺ OTf ⁻ ). How to promote. 9. A step of: (a) forming a sensitivity enhancing film on a base; (b) forming a chemically amplified resist film by coating a chemically amplified resist on the sensitivity enhancing film; (c) Subjecting said chemically amplified resist film and said sensitivity promoting film to radiation exposure, heat treatment and development to form a resist mask. 10. The pattern forming method according to claim 9, wherein an acid generating film is used as the sensitivity promoting film. 11. The pattern forming method according to claim 10, wherein the acid generating film is formed of SiO _4-n (OR) _n.
(However, R represents an alkyl group, and n is an integer satisfying 0 ≦ n <4. When n is 2 or more, R may be the same or different.) A resin containing a structure and an acid A pattern forming method comprising forming a film comprising a generating agent. 12. The pattern forming method according to claim 9, wherein the chemically amplified resist film is a positive resist. 13. The pattern forming method according to claim 9, wherein the chemically amplified resist film is a negative resist. 14. The pattern forming method according to claim 11, wherein triphenylsulfonium triflate (Ph ₃ S ⁺ OTf ⁻ ) is used as the acid generator. 15. The pattern forming method according to claim 9, wherein the base is constituted by an oxide film on a substrate, and the chemically amplified resist film is a positive resist.
(D1) After the step (c), using the resist mask, the sensitivity promoting film and the oxide film in an exposed region are removed by etching using a dry etching method to form a sensitivity promoting film pattern on the lower surface of the resist mask. And (e1) removing the resist mask, and (f1) baking the remaining structure including the sensitivity enhancement film to oxidize the sensitivity enhancement film pattern. Changing to a film pattern. 16. The pattern forming method according to claim 9, wherein the base is constituted by an oxide film on a substrate and the chemically amplified resist film is a positive resist.
(D2) After the step (c), using the resist mask, the sensitivity promoting film and the oxide film in an exposed region are removed by dry etching to form a sensitivity promoting film pattern and an oxide film pattern. Step (e2)
Thereafter, a step of removing the resist mask, (f)
2) a step of removing the sensitivity promoting film pattern.