JP2003035952A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resist pattern having a good shape by diminishing outgas produced from a resist film when the resist film comprising a chemical amplification type resist material is irradiated with extreme-ultraviolet radiation. SOLUTION: A resist film 11 comprising a chemical amplification type resist material having a base resin containing at least one selected from a t-butyl group, a t-butyloxycarbonyl group and a t-butyloxycarbonylmethyl group as a protective group and an acid generator is formed and patternwise exposed by irradiation with extreme-ultraviolet radiation (13.5 nm band) 13. The patternwise exposed resist film 11 is developed to form the objective resist pattern 14 having a good section shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method used in a semiconductor integrated circuit manufacturing process.

[0002]

2. Description of the Related Art With the increasing integration of semiconductor integrated circuits and downsizing of semiconductor devices, it is desired to accelerate the development of lithography technology.

At present, a pattern is formed by lithography using a mercury lamp, a KrF excimer laser, an ArF excimer laser, or the like as exposure light, but a fine pattern having a pattern width of 0.1 μm or less, particularly 50 nm or less is formed. In order to form the film, it has been considered to use extreme ultraviolet rays (wavelength: 1 to 30 nm) having a shorter wavelength than the exposure light as the exposure light. This is because it is required to prolong the life of a pattern forming method using exposure light, which is excellent in mass productivity.

The conventional pattern forming method will be described below.
This will be described with reference to FIGS.

First, a chemically amplified resist material having the following composition is prepared.

Poly ((2-methyl-2-adamantyl methacrylate) (70 mol%)-(methyl methacrylate) (20 mol
%)-(Methacrylic acid) (10 mol%)) (base resin) ………
2g Triphenylsulfonium triflate (acid generator) ………… 0.04g Propylene glycol monomethyl ether acetate (solvent) …… 20g

Next, as shown in FIG. 3A, the above chemically amplified resist material is applied onto the substrate 1 to form 0.2.
After forming the resist film 2 having a thickness of μm, FIG.
As shown in (b), pattern exposure is performed by irradiating the resist film 2 with extreme ultraviolet rays (wavelength: 13.5 nm band) using a reflective photomask (not shown) having a desired pattern. Do.

Next, as shown in FIG. 3C, the substrate 1 is heated at 110 ° C. by a hot plate (not shown).
At 60 ° C for 60 seconds to apply P to the resist film 2.
Perform EB. By doing so, the exposed portion 2a of the resist film 2 is changed to be soluble in an alkaline developing solution because acid is generated from the acid generator, while the unexposed portion 2b of the resist film 2 is changed from the acid generator to acid. Since it does not occur, it remains sparingly soluble in an alkaline developing solution.

Next, with respect to the resist film 2, 2.38 w
When developed with an alkaline developer containing t% tetramethylammonium hydroxide, FIG.
As shown in (d), a resist pattern 5 having an unexposed portion 2b of the resist film 2 and having a pattern width of 0.07 μm is formed.

[0010]

By the way, as a resist material in a pattern forming method using extreme ultraviolet rays as exposure light, a chemically amplified resist excellent in resolution and sensitivity is suitable, but in this case, the resist material during exposure is used. It is necessary that the amount of outgas generated from the gas is small.

If the outgas generated during the exposure is adsorbed on the reflection mirror or the photomask of the optical system, the illuminance of the exposure light is lowered and the accuracy of the resist pattern is deteriorated.

Therefore, according to the conventional pattern forming method, as shown in FIG. 3D, the cross-sectional shape of the resist pattern 5 deteriorates.

When the cross-sectional shape of the resist pattern 5 deteriorates, there arises a problem that the shape of the wiring patterned using the resist pattern 5 deteriorates.

In view of the above, according to the present invention, a resist pattern having a good shape can be obtained by reducing the outgas generated from the resist film when the resist film made of the chemically amplified resist material is irradiated with extreme ultraviolet rays. The purpose is to do so.

[0015]

In order to achieve the above-mentioned object, the first pattern forming method according to the present invention provides a t-butyl group, a t-butyloxycarbonyl group and a t-butyloxycarbonyl group as a protective group. A step of forming a resist film made of a chemically amplified resist material having a base resin containing at least one of methyl groups and an acid generator, and irradiating the resist film with extreme ultraviolet rays having a wavelength of 13.5 nm band Then, the step of performing pattern exposure and the step of developing the pattern-exposed resist film to form a resist pattern are provided.

According to the first pattern forming method, the protective group contained in the base resin is at least one of a t-butyl group, a t-butyloxycarbonyl group and a t-butyloxycarbonylmethyl group and has a capacity of Is relatively small, the film loss of the resist film when the protective group is eliminated can be suppressed to 10% or less. Therefore, almost no outgas is generated from the resist film when the extreme ultraviolet rays are irradiated, so that a resist pattern having a good cross-sectional shape can be obtained.

The second pattern forming method according to the present invention is
A step of forming a resist film made of a chemically amplified resist material having a base resin and 10% by weight or more of an acid generator with respect to the base resin, and the resist film is irradiated with extreme ultraviolet rays having a wavelength of 13.5 nm band. Then, the step of performing pattern exposure and the step of developing the pattern-exposed resist film to form a resist pattern are provided.

According to the second pattern forming method, since the weight ratio of the acid generator to the base resin is 10% or more, the sensitivity of the exposed portion of the resist film when irradiated with extreme ultraviolet rays is improved, and therefore the protective group is protected. It is possible to suppress the amount of film loss in the exposed portion of the resist film at the time of desorption of 10% or less. Therefore, almost no outgas is generated from the resist film when the extreme ultraviolet rays are irradiated, so that a resist pattern having a good cross-sectional shape can be obtained.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A pattern forming method according to the first embodiment of the present invention will be described below with reference to FIGS.

First, a chemically amplified resist material having the following composition is prepared.

[0021]   Poly ((t-butylmethacrylate) (70mol%)-(methylmethacrylate) (20mol %)-(Methacrylic acid) (10mol%)) (base resin) ……………………………… 2g   Triphenylsulfonium triflate (acid generator) ……………… 0.04g   Propylene glycol methyl ether acetate (solvent) 20g

Next, as shown in FIG. 1A, the substrate 10
The chemically amplified resist material described above is applied to
After forming the resist film 11 having a thickness of 2 μm, as shown in FIG.
As shown in (b), pattern exposure is performed by irradiating the resist film 11 with extreme ultraviolet rays (wavelength: 13.5 nm band) using a reflective photomask (not shown) having a desired pattern. Do.

Next, as shown in FIG. 1C, the substrate 10
110 by hot plate (not shown)
PEB is performed on the resist film 11 by heating for 60 seconds at a temperature of ° C. By doing so, the resist film 11
In the exposed portion 11a, an acid is generated from the acid generator and the protective group of the base resin is eliminated, so that the exposed portion 11a changes to be soluble in an alkaline developing solution, while the unexposed portion of the resist film 11 is exposed. In 11b, no acid is generated from the acid generator, so that the unexposed portion 11b remains sparingly soluble in the alkaline developer.

Next, with respect to the resist film 11, 2.38.
When development is carried out using an alkaline developing solution composed of wt% tetramethylammonium hydroxide, the result shown in FIG.
As shown in (d), the unexposed portion 11b of the resist film 11
The resist pattern 14 having a pattern width of 0.07 μm and a good cross-sectional shape is formed.

According to the first embodiment, since the protective group contained in the base resin is a t-butyl group and has a relatively small capacity, the amount of reduction of the resist film 11 when the protective group is eliminated is 3%. % Can be suppressed. For this reason, almost no outgas is generated from the resist film 11 when the extreme ultraviolet rays 13 are irradiated, so that as shown in FIG.
The resist pattern 14 having a good cross-sectional shape can be obtained.

In the first embodiment, the t-butyl group is used as the protecting group having a relatively small capacity, but instead of this, a t-butyloxycarbonyl group or a t-butyloxycarbonylmethyl group is used. May be used, or a base resin containing at least one of a t-butyl group, a t-butyloxycarbonyl group and a t-butyloxycarbonylmethyl group may be used.

When a chemically amplified resist material having a base resin containing a t-butyloxycarbonyl group as a protective group is used, the amount of reduction of the resist film can be suppressed to about 5%, and t-butyloxy as a protective group. When a chemically amplified resist material having a base resin containing a carbonylmethyl group is used, the reduction amount of the resist film can be suppressed to about 3%, and outgas is almost generated from the resist film 11 when irradiated with extreme ultraviolet rays 13. You can turn it off.

(Second Embodiment) A pattern forming method according to a second embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to (d).

First, a chemically amplified resist material having the following composition is prepared.

[0030]   Poly ((2-methyl-2-adamantyl methacrylate) (70mol%)-(methyl Tacrylate) (20mol%)-(methacrylic acid) (10mol%)) (base resin) ………… 2g   Triphenylsulfonium triflate (acid generator) ……………… 0.2g   Propylene glycol monomethyl ether acetate (solvent) ………… 20g

Next, as shown in FIG. 2A, the substrate 20
The chemically amplified resist material described above is applied to
After forming the resist film 21 having a thickness of 2 μm, as shown in FIG.
As shown in (b), pattern exposure is performed by irradiating the resist film 21 with extreme ultraviolet rays (wavelength: 13.5 nm band) through a reflective photomask (not shown) having a desired pattern. Do.

Next, as shown in FIG. 2C, the substrate 20
110 by hot plate (not shown)
PEB is performed on the resist film 21 by heating at a temperature of 60 ° C. for 60 seconds. By doing so, the resist film 21
In the exposed area 21a, an acid is generated from the acid generator and the protecting group of the base resin is eliminated, so that the exposed area 21a changes to be soluble in the alkaline developing solution, while the unexposed area of the resist film 21 is removed. In 21b, no acid is generated from the acid generator, so that the unexposed area 21b remains sparingly soluble in the alkaline developer.

Next, with respect to the resist film 21, 2.38.
When development is performed using an alkaline developing solution composed of wt% tetramethylammonium hydroxide, FIG.
As shown in (d), the unexposed portion 21b of the resist film 21.
The resist pattern 24 having a pattern width of 0.07 μm and a good cross-sectional shape is formed.

According to the second embodiment, the weight ratio of the acid generator to the base resin is 10%.
Exposure part 21 of resist film 21 when irradiated with 3
Since the sensitivity of a is improved, the amount of film loss of the exposed portion 21a of the resist film 21 when the protective group is eliminated can be suppressed to about 6%. Therefore, almost no outgas is generated from the resist film 21 when the extreme ultraviolet rays 23 are irradiated, so that the resist pattern 24 having a good cross-sectional shape can be obtained as shown in FIG.

In the second embodiment, the weight ratio of the acid generator to the base resin is 10%. However, if the weight ratio of the acid generator to the base resin is 10% or more, the extreme ultraviolet rays 23 are generated. Resist film 2 when irradiated with
Since the sensitivity of the first exposed portion 21a is further improved, the outgas generated from the resist film 21 can be further reduced.

[0036]

According to the first or second pattern forming method of the present invention, the amount of reduction of the resist film when the protective group is eliminated can be suppressed to 10% or less, so that extreme ultraviolet rays can be prevented. Outgas is hardly generated from the resist film upon irradiation, so that a resist pattern having a good cross-sectional shape can be obtained.

[Brief description of drawings]

1A to 1D are cross-sectional views showing respective steps of a pattern forming method according to a first embodiment.

2A to 2D are cross-sectional views showing each step of the pattern forming method according to the second embodiment.

3A to 3D are cross-sectional views showing respective steps of a conventional pattern forming method.

[Explanation of symbols]

10 substrates 11 Resist film 11a exposure unit 11b Unexposed part 12 Photomask 13 extreme ultraviolet 14 Resist pattern 20 substrates 21 Resist film 21a exposure unit 21b Unexposed part 22 Photomask 23 Extreme UV 24 resist pattern

Claims (2)

[Claims] 1. A base resin containing at least one of a t-butyl group, a t-butyloxycarbonyl group and a t-butyloxycarbonylmethyl group as a protecting group,
A step of forming a resist film made of a chemically amplified resist material having an acid generator; a step of irradiating the resist film with extreme ultraviolet rays having a wavelength of 13.5 nm band to perform pattern exposure; A step of developing the resist film to form a resist pattern. 2. A step of forming a resist film made of a chemically amplified resist material containing a base resin and 10% by weight or more of an acid generator with respect to the base resin, and the resist film having a 13.5 nm band. A pattern forming method comprising: a step of performing pattern exposure by irradiating extreme ultraviolet rays having a wavelength; and a step of developing the pattern-exposed resist film to form a resist pattern.