WO2006095705A1

WO2006095705A1 - Method of forming pattern

Info

Publication number: WO2006095705A1
Application number: PCT/JP2006/304313
Authority: WO
Inventors: Takashi Ubukata; Koji Takahashi; Yasushi Yokoyama
Original assignee: National University Corporation Yokohama National University
Priority date: 2005-03-09
Filing date: 2006-03-07
Publication date: 2006-09-14
Also published as: JPWO2006095705A1

Abstract

A method of forming a pattern with the use of a novel photosensitive composition capable of patterning through photoirradiation without undergoing development. A photosensitive composition comprising a photochromic compound having a ring capable of reversible ring opening-ring closure by light and/or heat so as to exhibit photochromism and a polymer compound as a matrix, the ring having the structure of the formula (I): (R1 and R2 are substituents and may form a ring; and R3 is a substituent) or the formula (II): (R4 and R5 are substituents) is provided and irradiated with rays containing ring opening wavelength ray capable of ring opening and ring closure wavelength ray capable of ring closure to thereby carry out a mass transfer of the photosensitive composition.

Description

Specification

Pattern formation method

Technical field

The present invention relates to a pattern forming method using a photosensitive composition, and in particular, a pattern using a photosensitive composition capable of forming a pattern only by light irradiation without performing a development step. It relates to the formation method.

Background art

The present inventors form a film using a composition containing a polymer compound having an azobenzene sensitive to light in the side chain and a liquid crystal molecule, and the film is irradiated with interference light to form a film. A technique for forming a relief grating (diffraction grating) is reported (see, for example, Patent Document 1 and Non-patent Document 1). According to this technique, since the film of the light irradiation part is transferred, it is possible to form a regular pattern only by light irradiation without passing through the development step.

Patent Document 1: Patent 3451319

Non-Patent Document 1: Yasushi Yokoyama, Shun Hikaru, "New Photochromic Systems and Applications of Photochromism", Future Materials, Inc. 'N' T's, 2004, 4th, 6th, p. 28-34 Disclosure of the invention

Problem that invention tries to solve

[0004] At the same time, when materials other than azobenzene are used, it has not been examined whether the ability to form a pattern by light irradiation is possible. Also, there is a problem that conventional patternable Azazobenzene composites have absorption in the visible range.

Accordingly, an object of the present invention is to provide a pattern formation method using a novel photosensitive composition capable of forming a pattern without development by light irradiation.

Means to solve the problem

That is, according to the pattern formation method of the present invention, ring-opened reversibly by light and Z or heat

-A pattern forming method using a photosensitive composition comprising a photochromic compound having a ring-closing ring and exhibiting photochromism, and a polymer compound to be a matrix, wherein the ring has the formula I [Formula 1]

(R, R may form a ring with a substituent, and R is a substituent)

one two Three

Or the formula II

[Formula 2]

(R, R is a substituent) has a structure shown by

4 5

The photosensitive composition is irradiated with light containing both the ring-opening wavelength light for ring-opening and the ring-closing wavelength light for ring-closing to cause mass transfer of the photosensitive composition.

[0006] When the photosensitive composition after pattern formation has absorption in the ultraviolet and visible region, it is preferable to irradiate light for reducing the absorption out of the ring-opening wavelength light or the ring-closing wavelength light.

Effect of the invention

According to the present invention, it is possible to form a pattern without development by light irradiation.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described.

[Photosensitive composition]

The photosensitive composition used in the present invention includes a photochromic compound which has a ring which is reversibly ring-closed by light and exhibits photochromism, and a polymer compound which becomes a matrix.

. Photochromism refers to the reversible conversion of a single chemical species between two stable states by light.

As the photochromic compound, the formula I

[Formula 1]

(R, R

1 2 may form a ring with a substituent R

3 is a substituent), or a compound of formula II

[Formula 2]

The compound which has a structure of (R, R is a substituent) can be illustrated.

4 5

[0011] As an operating temperature indicating photochromism, for example, room temperature can be mentioned.

In formula I, R is a substituent such as, for example, CH or N. Photok having a ring of Formula I

3

As a specific example of the oral compound, a compound represented by formula III

[Chemical 3]

Spiropyrans of the Formula IV

[Formula 4]

Spirooxazine represented by the formula V

Naphthovirane represented by the formula VI

[Chemical 6]

The spiropyran represented by these is mentioned.

As a compound of the above-mentioned formula III, for example, a compound in which R 1 CC H and R 1 RR NONO;

10 18 37 11 12 2 10

A compound wherein C H, R = H, R = NO; R = C H, R = H, R = NO, R

18 37 11 12 2 10 8 17 11 12 2 1

The compound which is = CH, R = H, R = NO is mentioned.

0 3 11 12 2

As a compound of the said Formula IV, the compound which is R = CH, CH, CH is mentioned, for example

13 3 8 17 18 37

Be

As a compound of the said Formula V, the compound which is R = R = CH, for example is mentioned.

14 15 6 5

As a compound of the above-mentioned formula VI, for example, the chemical formula R = C H, R = H, R = NO, R = S

16 18 37 17 18 2 19

Compounds include compounds wherein R = C H, R = H, R = NO, R = S.

16 8 17 17 18 2 19

Specific examples of photochromic compounds having a ring of Formula II include

[Chem. 7]

There are two kinds of Expression vm

[Formula 8]

And fulgide represented by

Examples of the compound of the above-mentioned formula VII include compounds in which R 1 = CH.

21 3

In addition, as the compound of the formula VIII, for example, R = CH, CH, CH, R;

And those having an aryl group such as a furan ring or an indole ring; and an aromatic ring such as a furan ring or an indole ring.

Specifically as a compound of formula VIII, Fulgide A

[Chem. 9]

Fnoregid C

[Formula 11]

Etc.

In the above formulas (III) to (VI), the UV light causes a ring opening reaction to the left and right to proceed, and the visible light reversibly causes a ring closure to the right and the left. In the above formulas VII to VIII, a cyclization reaction from left to right proceeds by UV light, and reversibly ring opening to the right by left light occurs by visible light. The thermal stability depends on the structure of the compound.

Matrix (polymer compound)>

The polymer compound serving as the matrix holds a predetermined shape of the photosensitive composition and serves as a binding agent when the composition is coated or the like. For example, a known matrix can be used. Specifically, for example, polyalkyl methacrylates, polyalkyl acrylates, polystyrenes, amorphous polyolefins, polyaryl alkylals and the like can be used. A photosensitive composition can be obtained by mixing these matrices with the above-mentioned photochromic compound and further appropriately blending predetermined solvents, additives and the like.

In terms of promoting the pattern formation by the photosensitive composition, the blending amount of the matrix is preferably as small as possible, and usually, the matrix is blended at about 20 parts by mass of LOO to 100 parts by mass of the photochromic compound.

Further, instead of mixing the matrix polymer compound with the photochromic compound, the photochromic compound may be polymerized to form a polymer photochromic compound. Examples of the skeleton of the polymeric photochromic compound include polyalkyl atalylate, polyalkyl methacrylate, polyester, polyamide, polybutyl alcohol and the like. Further, as a method for synthesizing the polymeric photochromic compound, radical polymerization, polycondensation, high molecular reaction and the like can be mentioned. When the photochromic compound is combined with the polymer, the content ratio of the matrix in the photosensitive composition can be reduced as compared with the case where the photochromic compound and the polymer compound are mixed, and the pattern formation is promoted. Preferred in terms of. [0019] (Addition of liquid crystal)

It is preferable to add a liquid crystal to the photosensitive composition used in the present invention because the photosensitive time can be greatly shortened. Examples of the liquid crystal include 4-Sinano 4'-pentyl biphenyl, 4-Sinano 4 ', 1-heptyl biphenyl, 4-Sinano 4' pentyloxy biphenyl, 4-Siano 4'-heptyl oxybiphenyl And N- (4-methoxybenzylidene) 4 butylaline which can be used as a nematic liquid crystal at the pattern formation temperature (eg room temperature to 60 ° C.) is not.

Although the compounding ratio of these liquid crystal molecules to the photosensitive composition is not particularly limited, for example, it is preferable to set the liquid crystal ratio to the photochromic compound to be 0.3 to 0.6. Here, the liquid crystal ratio refers to the mass ratio of the liquid crystal to the photochromic compound.

The photosensitive composition can form a coating film by, for example, coating using spin coating, and the composition of the dark part other than the irradiated part can be formed by irradiating light at a predetermined position of the coating film. A substance is moved to the bright part and gathered, or the composition of the irradiated part is moved so as to escape to the dark part or the like, thereby causing a pattern transfer. The mass transfer due to light irradiation depends on the type and structure of the photochromic compound. When the photosensitive composition gathers on a portion irradiated with light, a ridge is provided at the light irradiation portion, and when the photosensitive composition escapes from the light irradiation portion, a groove is formed in the light irradiation portion.

Then, when the photosensitive composition is irradiated with light including both the ring-opening wavelength light for forming a film of the photosensitive composition and ring-opening of the photochromic compound and the ring-closing wavelength light for ring-closing, for example, as described above The photosensitive composition in the irradiated part or the dark part can be moved by mass transfer to form a pattern.

For example, in the case of using the compound of the above-mentioned formula III, it is irradiated with light including both UV light for ring opening and visible light for ring closing. The irradiation light can be irradiated, for example, through a photomask of a predetermined pattern. Strictly speaking, for example, in the compound of the above-mentioned formula III, UV light also induces a ring closure reaction which is reduced only by the ring opening, so that the formation of asperities occurs even with pattern exposure of only ultraviolet light, and the following bombing effect can be induced. Therefore, light of a single wavelength can also be used as long as it is capable of simultaneously inducing ring opening and ring closing reaction. Here, the reason for irradiating both the ring-opening wavelength light and the ring-closing wavelength light is not clear, but is considered as follows. That is, in order to transfer the photosensitive composition in the irradiated part, the photochromic compound in the photosensitive composition repeats the ring-opening and 1-ring closure many times to change its conformation and make the whole composition flow by the bombing effect. It is thought that it is necessary. Therefore, even if only one of the ring-opening wavelength light and the ring-closing wavelength light is irradiated to advance either the ring-opening or ring-closing reaction, the mass transfer is not sufficiently performed! /.

Many of the photochromic compounds used in the present invention are stable and colorless, and are suitable, for example, for optical applications. In the case where the photosensitive composition after formation of notches has absorption in the visible region, it may be irradiated with light for reducing the absorption out of ring-opening wavelength light or ring-closing wavelength light.

In the case of using the compound of the above-mentioned formula III, the ring-opened compound (the compound on the right side of the formula 3) has a purple color. Then, as a result of irradiating both the ring-opening wavelength light and the ring-closing wavelength light for pattern formation, the photochromic compound in the photosensitive composition contains the ring-opening compound and the ring-closing compound at a constant ratio. For this reason, the photosensitive composition after noting formation will exhibit purple (it has an absorption spectrum in the ultraviolet visible region).

By the way, since a photochromic compound exhibits photochromism, if the ring-opened compound is changed to a ring-closed compound (the compound on the left side of Chemical formula 3) after pattern formation, the compound becomes colorless and does not absorb in the visible region. . Therefore, by irradiating visible light to the whole photosensitive composition after pattern formation, it changes to a ring-closing compound, and a photosensitive composition can be made transparent.

As described above, mass transfer occurs when the photochromic compound repeats ring-opening and ring-closing many times, so that the formed pattern does not return to its original state even when irradiated with only ring-closing wavelength light.

The action to reduce the UV-visible absorption spectrum of the photosensitive composition after the pattern formation described above is unique to the photosensitive composition of the present invention. In the case of the photosensitive composition using a conventional azovencene, the azovencene is changed to a cis-trans isomer which can not be opened by ring-closing ring closure by light, and the V-isomer is also absorbed in the UV-visible region, No action is obtained. Then, if the above-mentioned visible absorption is reduced after pattern formation using the photosensitive composition of the present invention, it is suitably applicable to, for example, a wavelength programmable organic DFB (distributed feedback type) laser element. That is, when a periodic diffraction grating provided inside a resonator of a DFB laser is patterned using the photosensitive composition of the present invention, oscillation is made in the visible region by reducing (or eliminating) visible absorption after noticing. It is possible to greatly improve the characteristics of the laser element having a frequency. For example, when the compound of the above-mentioned formula III is used, the characteristic of the laser element that oscillates the visible light wavelength is improved by eliminating the visible absorption spectrum.

The present invention is not limited to the above embodiment. For example, as the irradiation light, in addition to a photomask, interference exposure can also be used. Further, the photosensitive composition of the present invention can be applied to light switching materials because the physical properties are greatly changed by light. In addition, since the photosensitive composition of the present invention does not require development and can form a fine pattern by dry operation by light irradiation, it can be used, for example, as a diffraction layer of a wavelength programmable DFB laser which can be set on the user side.

. The photosensitive composition of the present invention is also applicable as a hologram material and a high density optical recording material.

Furthermore, since the photosensitive composition of the present invention is mass-transferred as a whole by light irradiation, it can also be applied as a carrier (conveyance) of an object to which substance transfer is desired. In this case, if the object is blended in the photosensitive composition, the photosensitive composition may be burnt out by firing or the like after irradiation with light.

Hereinafter, the present invention will be described in more detail by way of examples. The present invention is not limited to the following examples.

Example 1

Production of Photosensitive Composition>

Formula IX

[Formula 12]

Using a photochromic compound (spiropyran derivative) exhibiting photochromism as shown in the following, using polymethylmetatalylate (PMMA) as a matrix, 2.5 mass% of a spiropyran derivative in a solvent (cloform), and PMMA 1.7. The photosensitive composition was manufactured by adding% by mass. The above-mentioned spiropyran derivative opens when irradiated with UV light near 350 nm, and closes when irradiated with visible light near 550 nm. In the above spiropyran derivative, the ring-opened compound has a purple color, and the ring-closed compound is colorless and transparent.

The photosensitive composition was spin-coated on a flat glass substrate, and the solvent was evaporated to prepare a thin film having a thickness of 640 nm.

A light mask with a line width of 6.25 m in the light transmission area and a space width of 150 m is attached closely to the above film, and the light source power of a super high pressure mercury lamp is taken out by a long pass filter. ² ) I was irradiated for 2 hours.

The shape of the obtained pattern was measured by an atomic force microscope. The measurement results are shown in Fig.1.

As is apparent from FIG. 1, as a result of light irradiation using the above-mentioned photomask, a ridge structure having a width equal to that of the line and a height difference of 120 nm was formed.

Of the visible absorption spectrum of the photosensitive composition>

Next, the entire surface of the patterned photosensitive composition was irradiated with visible light having a wavelength of 540 nm or more (intensity: 0.06 WZ cm ² ), and only the ring closure reaction of the compound of formula IX was allowed to proceed. As shown in FIG. 2, the purple color (absorption wavelength 550 nm) of the photosensitive composition turned to be colorless and transparent, and the light absorption at a wavelength of 350 to 650 nm was reduced.

Example 2

A photochromic compound shown in Table 1 was blended with PMMA to prepare a photosensitive composition, and a pattern of ridge structures was formed in the same manner as in Example 1, and height differences of the ridges were measured. However, In the case of Example 2, a plurality of lattice masks constituting a repetitive pattern of light and dark with a period of 8 m were used as a photomask.

[table 1]

[0032] As apparent from Table 1, it was found that the compounds of Formulas III-VIII can be used to form a pattern.

Further, Samples 2 to 4 and Samples 5 to 7 in Table 1 have different molecular weights of substituents (linear alkyl groups) in the same complex. From these results, it was found that the height difference of the ridge becomes higher as the straight chain alkyl group which is a substituent is longer.

Example 3

[0033] (Effect of liquid crystal addition)

The compound of the formula IX (spiropyran derivative) used in Example 1 is incorporated as a photochromic compound in a dye concentration of 60% by mass, and 40% by mass of PMMA as a high molecular compound is incorporated, and 4-cyano-4, -pentylbiphenyl is further incorporated as a liquid crystal molecule. Liquid crystal ratio (Mass ratio of liquid crystal to spiropyran derivative) was mixed at 0.5 to prepare a photosensitive composition. The composition was spin coated on a flat glass substrate and the solvent was evaporated to form a thin film.

Photomasks with multiple grating masks that make up an 8 μm periodic pattern of light and dark The above thin film was subjected to mask exposure (light source, wavelength) for a predetermined time to form a concavo-convex pattern.

As a comparison, a concavo-convex pattern was formed in the same manner as described above except that the liquid crystal molecules were not added.

The obtained results are shown in Table 2.

[Table 2]

As apparent from Table 2, when a liquid crystal molecule is added to a photochromic compound to form a photosensitive composition, a concavo-convex pattern having an exposure time of 1 minute and a height difference of 100 nm or more can be formed. The

On the other hand, when liquid crystal molecules were not added to the photochromic compound, it took 2 hours of exposure time to form a concavo-convex pattern with a height difference of more than lOOnm.

Example 4

(Repeatment of unevenness formation and erasure)

Sample 7 dye concentration of 60 wt% as a photochromic compound, the PM MA 40 mass ^_0/0 blended as the polymer compound, further Puchirubifue to 4 Shiano 4 'single liquid crystal molecules - blending Le liquid crystal ratio 0.5, a solvent The photosensitive composition was prepared by diluting to a polymer concentration of 1.11% by mass. The composition was spin coated on a flat glass substrate and the solvent was evaporated to form a thin film.

Using a plurality of lattice masks constituting a repetitive pattern of light and dark with a period of 8 μm as a photomask, the thin film was subjected to mask exposure (light source, wavelength) for 20 minutes to form a concavo-convex pattern. The height difference of the ridges of this pattern was about 100 nm.

Next, the thin film after forming the concavo-convex pattern was heated on a hot plate at 56 to 58 ° C. for 30 minutes to eliminate the concavo-convex pattern. After disappearance, the thin film became almost flat.

Finally, when the thin film was subjected to the same mask exposure as above, the height difference was about 100 nm The concavo-convex pattern of is formed again.

Brief description of the drawings

[FIG. 1] It is a figure which shows the shape of the pattern obtained by light-irradiating to a photosensitive composition.

FIG. 2 is a view showing an absorption spectrum of the photosensitive composition before and after the patterned photosensitive composition is irradiated with visible light that causes only a ring closure reaction to proceed.

Claims

A pattern forming method using a photosensitive composition comprising a photochromic compound having a ring reversibly ring-closing ring closed by light and Z or heat and exhibiting photochromism and a polymer compound to be a matrix. The ring has the formula I

[Formula 1]

(R, R may form a ring with a substituent, and R is a substituent)

one two Three

Or the formula II

[Formula 2]

(R, R is a substituent) has a structure shown by

4 5

The pattern formation method which carries out mass transfer of the photosensitive composition by irradiating the photosensitive composition with light containing both the ring-opening wavelength light for ring-opening and the ring-closing wavelength light for ring-closing. The pattern formation method according to claim 4, wherein when the photosensitive composition after pattern formation has absorption in the ultraviolet and visible region, light of which the absorption is reduced among the ring-opening wavelength light or the ring-closing wavelength light is irradiated.