JPH0452648A - Resist pattern forming method - Google Patents

Abstract

PURPOSE:To improve the insolubility in a developer and to sharpen exposed patterns by subjecting a resist to a heating treatment while or after irradiating the entire surface of the resist with UV or far UV light. CONSTITUTION:The positive resist consisting of a radiation sensitive polymer contg. an azide compd. is applied on an Si wafer 1 and is then baked to form a resist film 2. After the film 2 is irradiated with the UV light, this wafer 1 is baked. The crosslinking reaction of the resist film is accelerated in this way. The film 2 is then irradiated with an electron beam to draw patterns. The film 2 is thereafter developed to remove the film 2 of the region irradiated with the electron beam, by which the resist pattern 3 is formed.

Description

[Detailed Description of the Invention] [Summary] Regarding a pattern forming method of a positive resist that realizes microfabrication, the present invention aims to suppress pattern deformation by improving the insolubility of a residual pattern (unexposed area) in a developer. A step of applying a positive resist made of a radiation-sensitive polymer containing an azide compound onto a substrate, a step of exposing the resist in a pattern to radiation, and developing the resist in the pattern-exposed area in a developer and exposing the resist to radiation. and a development step for removing the resist pattern in a portion,
A method for forming a resist pattern, comprising a step of heating the resist while or after irradiating the resist with ultraviolet light or deep ultraviolet light during a step before the developing step. This is what we provide.

[Industrial application field]

The present invention relates to a positive resist pattern forming method for realizing microfabrication.

2. Description of the Related Art Due to the recent demands for increased speed of semiconductor devices and associated miniaturization, it is desired to form extremely fine patterns with good controllability.

In forming fine patterns, exposure methods using X-rays, electron beams, or the like as a light source are expected.

(Prior Art) A method is known in which an acid compound is added to the resist used in the above exposure method to improve its insolubility in a developer.

After the resist added with the azide compound is applied onto the substrate, it is subjected to heat treatment, for example, in a nitrogen atmosphere.

At this time, the crosslinking reaction of the above resist increases due to the action of radicals generated from the added azide compound,
Increased insolubility in developer.

Therefore, reduction in the film thickness of the resist remaining as a pattern during development is suppressed.

[Problems to be Solved by the Invention] The resist is heat-treated to improve its insolubility in a developer.

By the way, in order to obtain a fine pattern, it is necessary to maintain a film thickness that can withstand the dry etching process after forming the fine pattern using resist, but when it comes to ultra-fine (submicron) patterns, it is necessary to maintain a sufficient film thickness after development. Since it was difficult to maintain a certain film thickness, although the reduction in film thickness was suppressed by adding an azide compound and heat treatment, it was not sufficient.

FIG. 2 shows a state in which a resist containing an azide compound is applied onto a silicon wafer 1, a pattern is exposed by X-ray irradiation, etc., the resist is thermally crosslinked by heat treatment, and then developed. It shows.

As is clear from FIG. 2, the film thickness of the resist pattern 4 after development is significantly reduced compared to the ideal pattern shown by the dotted line.

For example, when the resist film thickness before development was 3000, the residual resist film thickness after 3 minutes of development was 1500.

Reduction in film thickness or pattern deformation of a resist pattern due to development processing is a factor that causes a decrease in the reliability of various processes that are performed later using the resist pattern, so it is necessary to eliminate this problem. is an essential matter in order to obtain a fine pattern.

In view of the above-mentioned problems, an object of the present invention is to provide a pattern forming method that can maintain the film thickness of a resist pattern even after development.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a step of applying a positive resist made of a radiation-sensitive polymer containing an azide compound onto a substrate, a step of exposing the resist to radiation in a pattern, and a step of exposing the resist to radiation. A developing step of developing the resist in the region in a developer and removing the resist pattern in the exposed portion, and in the process before the developing step, while irradiating the resist with ultraviolet light or deep ultraviolet light, Alternatively, the present invention provides a method for forming a resist pattern, which includes a step of subjecting the resist to a heat treatment after irradiation.

[Function] In the present invention, a radiation-sensitive resist containing an azide compound is subjected to heat treatment while being irradiated with ultraviolet rays or far ultraviolet rays, or after being irradiated with ultraviolet rays.

The present inventors have discovered that by irradiating ultraviolet rays or deep ultraviolet rays in addition to the conventional heat treatment, a film retention rate greater than that obtained by heat treatment alone can be obtained.

In general, ultraviolet light or deep ultraviolet light is well known as a light source for exposure, and in positive resists, the irradiated area is dissolved by the developer, so the decomposition reaction occurs preferentially than the crosslinking reaction caused by the azide compound, resulting in crosslinking. It was thought that insolubilization due to

Experiments have shown that changing the heating time or heating temperature hardly improves the film retention rate, but when combined with ultraviolet light or deep ultraviolet light irradiation, the film retention rate is greatly improved. .

Therefore, the radicals generated by irradiation with ultraviolet light or deep ultraviolet light are considered to be a different type of radical from the radicals generated by heat treatment.

〔Example〕

Example 1 First, poly(trimethylsilylmethyl(α-trifluoromethyl)acryleto) CF represented by the following formula (1).

4,4゛-Diazidochalcone N3- [phase] CH=C)I-C-◎-N3 shown in the following formula (2) for the resist material consisting of
...... (2) is added to the polymer 7.
Add 30 g of MIBK (methyl isobutyl ketone) solution by weight.

Refer to FIG. 1(A) Next, after coating the above MIBK solution on the Si wafer 1,
A resist film 2 is formed by baking on a hot plate at 80° C. for 60 seconds.

The film thickness of the resist is approximately 3000.

The beta step is carried out for the purpose of evaporating the organic solvent in the resist, and as a result, the crosslinking reaction hardly progresses.

Refer to FIG. 1(B) After irradiating the resist film 2 on the wafer 1 with ultraviolet light for 30 seconds using a Xe-Hg lamp, the wafer 1 was
Hake for 60 seconds on a real plate at 0°C.

The ultraviolet light and heat applied in this step generate radicals from the and compound in the resist film, and as a result, the crosslinking reaction of the resist film is promoted.

FIG. 1(C) The resist film 2 is irradiated with an electron beam at a reference acceleration voltage of 20 KeV to draw a pattern.

The exposure pattern was a so-called line & 5 pace pattern in which lines with a width of 0.4 μm were formed at intervals of 0.4 μm.

Refer to FIG. 1(D), the resist film 2 is developed for 2 minutes using a developer made of isobutyl alcohol, and the resist film 2 in the area irradiated with the electron beam is removed.

When the pattern 3 of the resist film 2 obtained by the above process was observed, it was confirmed that a sharp 1-line & 5-pace pattern without pattern deformation was obtained.

The film thickness of the resist pattern 3 (unexposed area) according to this example is 2900 Å or more, and the remaining film rate is dramatically improved compared to the conventional crosslinking using only heat.

Example 2 7 of [・limethylsilylmethyl methacrylate and α-trifluoromethylacrylic acid represented by the following formula (3)]
: To a resist material consisting of a 3 copolymer, 5% by weight of an azide compound consisting of 4,4゛-diazidechalcone represented by the above formula (2) was added to the polymer, and 30 g/l of MrBK (methyl isobutyl ketone) was added. .

Next is the above MIBK? After applying the S liquid onto the Si wafer,
A resist film is formed by baking on a hot plate at 100°C for 100 seconds.

The film thickness of the resist is approximately 3000.

The baking step is performed for the purpose of evaporating the container solvent in the resist, and as a result, the crosslinking reaction hardly progresses.

Next, while irradiating the resist film on the wafer with ultraviolet light using an Xe-Hg lamp, the wafer was heated at 2 20
Beta for 6 minutes on a hot plate at 'C.

The ultraviolet light and heat applied in this step generate radicals from the azide compound in the resist film, and as a result, the crosslinking reaction of the resist film is promoted.

Next, the resist film is irradiated with an electron beam at an acceleration voltage of 20 KeV to draw a pattern.

The exposure pattern was a line and space pattern of Q, 4 μm.

Next, the resist film is developed for 3 minutes using a developer made of isopropyl alcohol, and the resist film in the area irradiated with the electron beam is removed.

When the pattern of the resist film obtained through the above steps was inspected, it was found that, as in Example 1, a sharp line and space pattern without pattern deformation was obtained.

Example 3 Trimethylsilylmethyl (α-
Even if a 6=4 copolymer of trifluoromethyl) acrylate and tert-butyl (α-trifluoromethyl) acrylate is used in place of the resist material represented by formula (3) in Example 2, similar effects can be obtained. was gotten.

Example 4 The above formula ( An azide compound consisting of 44'-diazidechalcone represented by 2) was added in an amount of 5% by weight based on the polymer to prepare a 30 g/j2 toluene solution.

Next, after applying the above toluene solution onto the Si wafer, 1
A resist film is formed by baking on a hot plate at 00°C for 100 seconds.

The film thickness of the resist is approximately 3000.

The baking step is performed for the purpose of evaporating the organic solvent in the resist, and as a result, the crosslinking reaction hardly progresses.

Next, the resist film is irradiated with an electron beam with an acceleration voltage of 20 KeV to draw a line & space pattern.

Next, the wafer was heated to 200°C while irradiating the resist film on the wafer with ultraviolet light using a Xe-Hg lamp.
was heated on a hot plate for 100 seconds.

The ultraviolet light and heat applied in this step generate radicals from the azide compound in the resist film, and as a result, the crosslinking reaction of the resist film is promoted.

Next, the resist film is developed for 2 minutes using a developer made of cyclohexane, and the resist film in the area irradiated with the electron beam is removed.

When the pattern of the resist film obtained by the above process was inspected, it was found that, as in Example 1, a sharp line and space pattern without pattern deformation was obtained.

As the azide compound, in addition to the azide compound shown by the above formula (2), similar effects can be obtained by using azide compounds shown by the following formulas (6) to 01).

N3-◎-0-◎-N3...(6
)N3-◎-(CHz)z-◎-N3 ・
・ ・ ・(7) N3-◎-CH2-◎-N:l
...(8) N3-◎-CH*CH-
C'・-N3...(9)N3-◎-CH
? C) I <Q>-N:l ...GO) CI(
.

N11-@-CH=CH-C-CH=C◎-N3
---Ol) (Effects of the Invention) As explained above, according to the present invention, not only thermal crosslinking by heat treatment but also crosslinking by ultraviolet light is performed, so that insolubility in developing solutions is improved and sharp An exposure pattern can be obtained.

FIG. 2 is a diagram illustrating a conventional problem.

In the figure, 1... 2... 3... It is.

...Wafer ...Resist film ...Resist pattern

[Brief explanation of drawings]

Figure 1 is a detailed diagram of the present invention, Figure 2 is a detailed diagram of the present invention Figure 1 (part 2) Figure 1 is a detailed diagram of the present invention (part 1)

Claims (3)

[Claims] (1) A step of applying a positive resist made of a radiation-sensitive polymer containing an azide compound onto a substrate, and then irradiating the entire exposed area of the resist with ultraviolet light or deep ultraviolet light, or after irradiating the resist. a step of heat-treating the resist, a step of pattern-exposing the resist with radiation, and a step of developing the pattern-exposed resist in a developer to remove the exposed portions of the resist pattern. Characteristic resist pattern formation method. (2) A step of applying a positive resist made of a radiation-sensitive polymer containing an azide compound onto a substrate, a step of exposing the resist in a pattern to radiation, and then exposing the entire exposed area of the resist to ultraviolet light or a long distance. A step of heat-treating the resist while or after irradiation with ultraviolet light, and a step of developing the pattern-exposed resist in a developer to remove the exposed portion of the resist pattern. Characteristic resist pattern formation method. (3) The resist pattern forming method according to claim (1) or (2), wherein the radiation-sensitive polymer is an acrylic polymer.