JPH08181132A - Formation of p-type pattern - Google Patents

Abstract

PURPOSE: To form a pattern having a superior dry etching resistance in the case where a short-wavelength exposure light source is used by a method wherein an active radiation is irradiated on a resist film containing substantially an aromatic ring-containing substituting group and a high-molecular compound, which is formed with a structure, wherein oxygen atoms are bonded together to silicon atoms, as a unit, as its main components. CONSTITUTION: A diazonaphthoquinone-novolak resin P-type photoresist is applied on a silicon substrate 1 and the photoresist is baked for 20 minutes or thereabouts at a temperature of 200 deg.C or thereabouts to form a lower resist film 2 of a film thickness of one micron or thereabouts. A polyhydroxy benzyl silusesquioquixane is applied on this resist film 2 and the polyhydroxy benzyl silusesquioquixane is baked for 20 minutes or thereabouts at a temperature of 80 deg.C or thereabouts to form an upper resist film of a film thickness of 300nm or thereabouts. An ArF excimer laser beam 5 is irradiated on this two-layer resist film in the atmosphere 4. Whereupon at the time of the irradiation dose of 1200mJ/cm<2> or thereabouts of the laser beam 5, the irradiated part of the resist film is completely evaporated and a P-type resist pattern 3 having a good dry etching resistance is formed on the upper resist film.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a short wavelength radiation source A
The present invention relates to a resist pattern forming method suitable for deep ultraviolet lithography using an excimer laser such as rF or KrF as a light source.

[0002]

2. Description of the Related Art Recently, a self-developing method, which is a kind of dry development of resist, has been studied. The self-developing method is a method in which the resist film in the irradiated area is directly evaporated by photo-etching by irradiation with radiation, and a resist pattern is obtained without using a developing solution. Since wet development is unnecessary, the number of lithography process steps is reduced. it can. Radiation used for this dry development includes light, electron beams, X-rays, and the like. In this method, the stronger the absorption of the resist, the more the amount of evaporation due to radiation irradiation increases. Therefore, when an ArF laser (193 nm) having a short wavelength is used as an exposure source, an aromatic resin that does not have a silicon atom, such as triphthalaldehyde, which exhibits strong absorption near 200 nm, is used as a resist. .

[0003]

However, conventional aromatic resins lack dry etching resistance. That is, the resist itself is damaged when the film immediately below the resist is etched. In particular, an object of the present invention is to provide a pattern having excellent dry etching resistance when an exposure source having a short wavelength is used, in which damage is more remarkable as a resist made of a resin having high self-developing sensitivity. It is in.

[0004]

Means for Solving the Problems The above-mentioned object is to provide a resist film containing as a main component a polymer compound whose unit is a structure in which a substituent containing an aromatic ring and an oxygen atom are bonded to a silicon atom, This can be achieved by irradiating with actinic radiation to volatilize the resist film in the irradiated portion.

[0005]

In the present invention, a polymer compound having a structure in which an aromatic functional group directly contacts a silicon atom and the silicon atom has at least one Si—O bond is irradiated with active actinic radiation. There is. This Si-O bond has a strong chemical bond, and when a resist having a Si-O bond is used, it exhibits excellent resistance to dry etching. The dry etching resistance is excellent even in an oxidizing atmosphere such as oxygen plasma.

In addition, the resist film thickness is 20 per micron.
When activated actinic radiation is irradiated so as to have the above absorbance, the polymer compound of the resist absorbs light very efficiently.
Therefore, the photochemical reaction and the thermal reaction after absorption of light in the light irradiation section efficiently cause decomposition and evaporation of the polymer compound.

FIG. 1 shows the evaporation amount when a polymer compound is irradiated with ArF excimer laser. The horizontal axis of FIG. 1 is the light irradiation amount (mJ / cm ² ) and the vertical axis is the evaporated film thickness (nm). From FIG. 1, at the wavelength of the ArF excimer laser, the aromatic polysilsesquioxane having an absorbance of 20 per 1 μm of film thickness is 1000 mJ / c.
At the irradiation amount of m ² , the evaporated film thickness was about 100 nm. On the other hand, non-aromatic polysilsesquioxane is
Less than 0.3 absorbance / micron, 2000mJ / c
No evaporation of the film was observed even at a dose of m ² .
As described above, when a polymer compound having a structure having an aromatic functional group and a Si—O bond as a unit is irradiated with light having a wavelength at which the absorbance is 20 or more per 1 μm of film thickness, the light irradiation unit is efficient. It is well photo-evaporated. On the other hand, no reaction occurs in the non-irradiated part. As a result, a positive resist pattern can be obtained only by light irradiation without going through a developing process.

An example of the polymer compound of the present invention is shown in FIG.
Shown in Here, at least one of R1 and R2 is an aromatic functional group. R1 and R2 may be the same or different. In addition, as another example of the polymer compound, FIG.
Examples thereof include polysiloxane represented by the general formula shown in (b). At least one of R1 and R2 in FIG.
One is an aromatic functional group. R1 and R2 may be the same or different. R3 is a hydrogen atom, a hydroxyl group, or an aliphatic functional group. Further, n is a positive integer.
Further, examples of the polymer compound include homopolymers or copolymers of polysilsesquioxane represented by the general formula shown in FIG. 3 (c). In FIG. 3 (c), at least one of R1, R2, R3, and R4 is an aromatic functional group. R1, R2, R3 and R4 may be the same or different. Further, n is a positive integer.

Specifically, a phenyl group, which is one of the aromatic substituents, and a derivative thereof in which phenylsiloxane is directly bonded to a Si atom, a homopolymer of phenylsilsesquioxane, a copolymer, or the like can be used. . Further, not only the above-mentioned phenyl group derivative but also a functional group having a 6-membered ring skeleton such as benzyl group, phenethyl group, styryl group, cinnamyl group, benzhydryl group and derivatives thereof can be used. As the aromatic substituent, a functional group having an aromatic ring such as naphthalene or anthracene skeleton, a derivative thereof, or a heterocyclic aromatic substituent can be used.

As the irradiation light source, a deuterium lamp, SOR
Light and UV laser are possible. The pulsed laser light typified by an excimer laser has a larger irradiation energy per unit time than the stationary light of a lamp or the like, and an enormous amount of light is emitted in a short time of about one tens of nanoseconds for emitting one pulse. Intrigued by molecular compounds. Therefore, due to heat and light absorption,
The polymer evaporates efficiently. Therefore, a pulse laser is desirable as the irradiation light source. Moreover, the atmosphere for irradiating the laser beam may be in the air, in a vacuum, or in an inert gas.

When the aromatic group substituent of the polymer compound is a 6-membered ring derivative represented by a phenyl group, the wavelength of the irradiation light has a strong absorption band of the 6-membered ring derivative at 200 nm.
UV light in the vicinity is suitable. Particularly, the ArF excimer laser (wavelength 193 nm) is most suitable as the light source. Also,
When the aromatic substituent is a naphthalene derivative, 250 n
UV light around m is good, and a KrF excimer laser (wavelength 248 nm) is suitable for irradiation.

Further, the transfer mask pattern is effective as the upper layer resist pattern of the two-layer resist method. At this time,
A heat-treated polymer film can be used as the lower resist film. For the transfer to the lower layer, it is possible to use photo-oxidative etching in an oxidizing atmosphere such as oxygen or ozone, in addition to reactive ion etching of oxygen.

Further, since the aromatic silicon polymer compound used in the present invention does not need to incorporate a complicated chemical reaction system, it is easy to handle since it is less susceptible to environmental changes and changes over time.

[0014]

【Example】

(Example 1) The ladder-type polyphenylsiloxane shown in FIG. 3D (where n is a positive integer) was dissolved in 1-butanol to prepare a 6.7 wt% solution. This solution was spin-coated on a silicon substrate and prebaked at 100 ° C. for 3 minutes to obtain a thin film having a thickness of 90 nm.

Next, the thin film was irradiated with ArF excimer laser (wavelength 193 nm) in the atmosphere. At this time,
The condition was that the energy per pulse was 120 mJ and the repetition frequency was 2 Hz. As a result, irradiation dose 1000m
At J / cm 2, the thin film in the irradiated area was completely evaporated, and a good 0.25 micron positive line-and-space pattern could be formed. Light irradiation amount is 1000 mJ /
When it was less than cm2, a thin film residue was observed in the irradiated part.

(Example 2) In Example 1, instead of the ladder-type polysiloxane, the alcohol solution of the linear polyphenylsiloxane shown in FIG. 3 (e) (where n is a positive integer) was used as a silicon substrate. Spin coating to 100
nm thin film was formed. This thin film was irradiated with ArF excimer laser in vacuum to obtain a good positive type pattern.

By irradiating in a vacuum in this way,
Evaporates more efficiently than irradiation in other atmospheres.

(Example 3) Instead of irradiating the ArF excimer laser light of Example 1 in the atmosphere, irradiation was performed in nitrogen gas at 1 atm, and as a result, a good positive type pattern was obtained. By irradiating in the nitrogen gas in this way, the resist surface is less likely to be altered as compared with the case of irradiating in the atmosphere.

(Embodiment 4) FIG. 2 shows a method of forming a two-layer resist pattern using the present invention. A diazonaphthoquinone-novolak resin-based positive photoresist was spin-coated on a silicon substrate and hard-baked at 200 ° C. for 20 minutes to form a lower resist film having a thickness of 1 μm. Next, polyhydroxybenzylsilsesquioxane was spin-coated on this resist film and baked at 80 ° C. for 20 minutes to form an upper resist film having a film thickness of 300 nm. When the two-layer resist is used in this manner, the surface can be flattened by forming the lower layer resist, so that the pattern can be formed even if the resist base has surface irregularities.

This two-layer resist film was irradiated with ArF excimer laser in the atmosphere under the same conditions as in Example 1.
As a result, when the irradiation amount was 1200 mJ / cm ² , the resist film in the irradiation portion was completely evaporated, and a good positive resist pattern could be formed in the upper layer. In FIG. 2, 1 is a silicon substrate, 2 is a lower resist film, and 3 is an upper resist pattern formed by ArF excimer laser irradiation.

Next, this substrate was placed in a resist stripping apparatus equipped with a 120 w low-pressure mercury lamp, and photooxidation etching of the lower layer resist was performed using the upper layer resist pattern as a mask while irradiating light in an oxygen atmosphere for 40 minutes. It was In FIG. 2, reference numeral 4 indicates an oxidizing atmosphere. Further, reference numeral 5 indicates a photo-oxidizing ray. In the photo-oxidative etching process, since the upper resist coating portion contains silicon, nonvolatile silicon dioxide was formed by photo-oxidation and the etching did not proceed. On the other hand, in the part where the lower layer resist is exposed without the upper layer resist, the lower layer resist effectively absorbs light to cause photo-oxidation, and is finally removed (etched) by burning, and is removed on the silicon substrate surface. The photo-oxidation etching proceeded sequentially until it was reached. As a result of SEM observation after completion of photo-oxidation etching, a lower layer resist pattern in which the upper layer resist pattern was faithfully transferred could be formed. As described above, the wet development that is usually performed by photo-oxidizing the lower layer resist is not necessary, and both the upper layer resist and the lower layer resist can be dry-processed.

[0022]

According to the present invention, it is possible to form a pattern having excellent dry etching resistance when short-wavelength activated actinic radiation is used.

[Brief description of drawings]

FIG. 1 is a diagram showing an evaporation amount when a polysilsesquioxane is irradiated with an ArF excimer laser.

FIG. 2 is a diagram showing a pattern forming method by a two-layer resist process used in Example 4 of the present invention.

FIG. 3 is a diagram showing a general formula of a polymer compound as a main component in the resist of the present invention.

[Explanation of symbols]

1 ... Silicon substrate, 2 ... Lower layer resist, 3 ... Upper layer resist pattern, 4 ... Oxidizing atmosphere, 5 ... Photo-oxidizing light beam.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroshi Fukuda 1-280 Higashi Koigokubo, Kokubunji, Tokyo Metropolitan Research Laboratory, Hitachi Ltd. (72) Tsuneo Terasawa 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi Ltd. Central Research Center

Claims (11)

[Claims] 1. A process of forming a resist film on a substrate, the resist film containing as a main component a polymer compound having a structure in which a substituent containing an aromatic ring and an oxygen atom are bonded to a silicon atom as a unit, and an activity. By irradiating the resist film with actinic radiation,
And a step of volatilizing the resist film in the irradiated portion. 2. The method for forming a positive pattern according to claim 1, wherein the irradiation is such that an absorbance of 20 or more per micron of the resist film is obtained. . 3. The method for forming a positive pattern according to claim 1 or 2, wherein the polymer compound is represented by the general formula (1): (At least one of R1 and R2 is represented by an aromatic functional group). 4. The method for forming a positive pattern according to claim 3, wherein R1 and R2 are the same. 5. The method for forming a positive pattern according to claim 1 or 2, wherein the polymer compound is represented by the general formula (2): (At least one of R1 and R2 is an aromatic functional group, R3
Is a hydrogen atom, a hydroxyl group, or an aliphatic functional group, n
Is a polysiloxane represented by a positive integer). 6. The method for forming a positive pattern according to claim 1, wherein the polymer compound is represented by the general formula (3): A positive type pattern characterized by being a homopolymer or copolymer of polysilsesquioxane represented by (at least one of R 1, R 2, R 3 and R 4 is an aromatic functional group, n is a positive integer). Forming method. 7. The positive pattern forming method according to claim 1, wherein the actinic radiation is ArF excimer laser light. 8. The method for forming a positive pattern according to claim 7, wherein the ArF excimer laser beam has a wavelength of 193 nm. 9. The positive pattern forming method according to claim 1, wherein the irradiation is performed at 1000 mJ / cm ² or more. 10. A process of forming a first resist film on a substrate, and a polymer compound having a structure in which a substituent containing an aromatic ring and an oxygen atom are bonded to a silicon atom as a unit are substantially main components. Forming a second resist film on the first resist film, and irradiating the second resist film with actinic radiation to volatilize the resist film in the irradiated portion. And a step of etching the first resist film using the second resist film as a mask. 11. The pattern forming method according to claim 5, wherein the etching uses photo-oxidation.