JP2000009955A - Metal oxide thin film pattern forming method and metal oxide thin film pattern forming composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a refractive index distribution of an inorganic optical waveguide, a photonic band, an interference mirror, etc. having a small propagation loss and excellent heat resistance, and a surface imaging step in semiconductor fine processing, Useful for forming fine metal wiring patterns,
Provided is a method for forming a metal oxide thin film pattern. SOLUTION: A step of forming a photosensitive layer containing a sublimable organometallic complex and a silicon-based polymer compound on a substrate, selectively exposing a predetermined region of the photosensitive layer to a latent image of a thin film pattern And a step of heating and drying the photosensitive layer on which the latent image of the thin film pattern is formed to remove an unexposed sublimable organometallic complex. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a metal oxide thin film pattern, and more particularly to an optical fiber, an optical waveguide, a semiconductor laser (LD), and a photodiode (P).
D) Optical waveguides that are optically coupled to optical elements such as lenses or the like, or fine and periodic refractive index distribution patterns such as photonic bands and interference mirrors, and surface imaging methods used for forming fine metal patterns and semiconductor fine processing. The present invention relates to a method for forming a metal oxide thin film pattern and a composition used for the same.

[0002]

2. Description of the Related Art Surface-mount type optical waveguides have been energetically developed for the purpose of applying optical / electrical hybrid multi-chip modules for conventional high-speed broadband communication systems and optical interconnection technology. . Such optical waveguides are expected to be applied to a wide range of applications, from in-chip wiring having a wiring length of several millimeters or less, to module wiring having a length of about several centimeters, and further to optical wiring in a board having a length of about several tens of centimeters.
Such an optical wiring is hardly affected by electromagnetic noise and generates a very small amount of electromagnetic noise. Moreover, it is expected that the importance will be further increased in the future, for example, a decrease in processing speed due to signal delay or the like can be significantly suppressed.

Various types of surface-mounted optical waveguides from organic materials to inorganic materials have been studied as described above. For example, those using organic polymers such as acrylic resin can be molded relatively easily,
There is an advantage that a processing process can be performed at a low temperature without deteriorating a nonlinear optical dye or the like. However, organic polymers such as acrylic resins are inferior in heat resistance, and at present, heat resistance is not sufficiently improved by using polyimide or the like. In addition, propagation loss in the infrared region is large due to infrared absorption generally caused by carbon-hydrogen bonds present in many organic compounds. Although the propagation loss can be reduced by replacing the carbon-hydrogen bond with the carbon-fluorine bond, there is a problem in terms of cost in this case.

On the other hand, an inorganic optical waveguide mainly composed of silicon dioxide has excellent properties such as excellent heat resistance and low propagation loss in the infrared region. However, a general method of manufacturing a silicon dioxide-based optical waveguide requires a complex multi-step lithography process including a CVD process and an RIE process.

[0005] In view of the above, there is a need for a processing process for easily producing an inorganic optical waveguide having excellent optical characteristics at a low cost and at a relatively low temperature. Examples of such a processing process include forming a photosensitive layer by applying a metal oxide sol whose reactivity has been suppressed by modifying it with an organic ligand such as acetylacetone to form a photosensitive layer, and exposing the organic ligand to light by pattern exposure. A method of obtaining a negative pattern of a metal oxide by decomposing to promote crosslinking of the gel in the exposed portion and washing and removing the unexposed portion has been proposed (Shinge et al., Jpn. Appl. Phys., 33, L1181
(1994)). Furthermore, after pattern exposure of the polysilane film and selective infiltration of the metal oxide sol into the photooxidized exposed portions, the entire surface is exposed to oxidize the polysilane and finally removed by washing to remove the metal oxide thin film pattern. Is disclosed (Japanese Patent Application Laid-Open No. 7-92695). In these methods, a metal oxide pattern can be formed by a relatively simple process, but a clad layer must be separately formed except for using an air layer as a clad. In the latter method, the hydrocarbon group bonded to the side chain of the polysilane may remain and the propagation loss may increase. Further, since a reactive group such as a hydroxyl group is required in the sol, the storage stability of the sol liquid is reduced. Sex was a problem.

[0006] In the above-mentioned method using solvent development, it is extremely difficult to manufacture an element such as a photonic band structure or an interference mirror, which requires a periodic change in the refractive index in the film thickness direction. For example, in the case of a multilayer optical / electrical hybrid chip, a reflecting mirror formed at an angle of 45 ° with respect to the substrate is indispensable to extract light in a direction perpendicular to the substrate. As such a reflecting mirror, an interfering mirror having a periodic refractive index distribution in order to increase the reflection efficiency is preferable. However, the interfering mirror must be
In this case, it is necessary to form a fine refractive index distribution at a desired position of the waveguide film in a direction inclined by 45 ° from the film thickness direction. However, it is very difficult to form such a three-dimensional refractive index distribution by a conventional method using a CVD process, an RIE process, or the like, or a solvent developing method.

As a method for forming a refractive index distribution in an inorganic substance without using solvent development, a method using a metal porous film impregnated with a photosensitive organic metal compound is disclosed (S).
PIE Proceedings, 2288, 580-588 (199
4)). In this method, a photosensitive film is formed by impregnating a porous metal oxide film formed by a sol-gel method with a photoreactive organometallic compound, and this film is subjected to pattern exposure to expose a photosensitive organic film in an exposed portion. Photodecomposes metal compounds. The photodecomposed metal compound in the exposed portion is chemically bonded to the porous film, while the unexposed portion is volatilized by a method such as heating. For this reason, when heated after exposure, the exposed portion is in a state where the metal species derived from the organometallic compound is doped in the metal oxide matrix, and a refractive index pattern can be formed.

By using this method, it is possible to form a refractive index distribution in an inorganic substance without developing with a solvent. However, the sol-gel solution for forming the sol-gel film has insufficient storage stability, and requires a heat treatment at a high temperature of 700 ° C. or more to densify the metal porous film. could not.

[0009]

As described above, in the conventional method of manufacturing an inorganic optical waveguide, a CVD process or an RIE
There is a need for a complex and relatively high temperature process including steps. In the case of the manufacturing method including the coating step, it is necessary to separately form a cladding layer, and the propagation loss is large due to the residual polysilane side chains. In addition, since the sol liquid does not have sufficient storage stability, process control and quality control are complicated, and in addition, a three-dimensional fine refractive index distribution in the film thickness direction such as a photonic band or an interference mirror is formed. It was extremely difficult to do.

Accordingly, the present invention provides an inorganic optical waveguide, a photonic band, a refractive index distribution of an interference mirror, etc., having a small propagation loss and excellent heat resistance. It is an object of the present invention to provide a method useful for forming a wiring pattern and capable of easily forming a metal oxide thin film pattern.

Another object of the present invention is to provide a composition for forming a metal oxide thin film pattern as described above. Still another object of the present invention is to provide a method for easily forming a fine metal wiring pattern in semiconductor fine processing.

[0012]

Means for Solving the Problems To solve the above problems, the present invention provides a process for forming a photosensitive layer containing a sublimable organometallic complex and a silicon-based polymer compound on a substrate, Selectively exposing a predetermined area to form a latent image of a thin film pattern, and heating and drying the photosensitive layer on which the latent image of the thin film pattern has been formed, to obtain a sublimable organometallic complex in an unexposed portion. A method for forming a pattern of a metal oxide thin film, comprising:

The present invention also provides a composition for forming a metal oxide thin film pattern, comprising a sublimable organometallic complex and a silicon-based polymer compound. Further, the present invention, on the substrate,
Forming a photosensitive layer containing a sublimable organometallic complex, selectively exposing a predetermined region of the photosensitive layer to form a latent image of a thin film pattern, and forming a latent image of the thin film pattern on the photosensitive layer. A method for forming a metal fine pattern comprising a step of heating and drying a layer to remove a sublimable organometallic complex in an unexposed portion and a step of depositing a metal in an exposed portion of the photosensitive layer after the heating and drying. .

Hereinafter, the present invention will be described in detail. In the pattern forming method of the present invention, when a predetermined region of the photosensitive layer formed on the substrate is selectively exposed, the sublimable organometallic complex contained in the exposed portion of the photosensitive layer is sublimable by photolysis or the like. To lose. At the same time, through a reaction such as hydrolysis, the sublimable organometallic complex bonds with the silicon-based polymer compound of the matrix, and a latent image is formed on the photosensitive layer. Thereafter, when the photosensitive layer is dried by heating, preferably by vacuum heating, the sublimable organometallic complex is sublimated and removed from the matrix composed of the silicon-based polymer compound in the unexposed portion of the photosensitive layer. On the other hand, in the exposed portion of the photosensitive layer, the sublimable organometallic complex is decomposed and does not sublime even when heated, and the central metal remains in the form of an oxide or the like. As a result, the exposed portion of the photosensitive layer is in a state where the silicon-based polymer compound is doped with the central metal element of the sublimable organometallic complex, and such a state does not occur in the unexposed portion. Thus, a pattern of a metal oxide thin film applicable to a refractive index distribution type optical waveguide pattern or the like can be formed at the exposed portion and the unexposed portion of the photosensitive layer. At this time, since the matrix in which the sublimable organometallic complex is dispersed is a fine resin layer that is not porous, the processing accuracy is good and a fine pattern can be formed.

In the method for forming a metal oxide thin film pattern according to the present invention, first, a photosensitive layer containing a sublimable organometallic complex and a silicon-based polymer compound is formed on a substrate. The base material may be flat or curved, and its material is not limited at all. For example, any substrate on which a metal oxide thin film pattern can be formed, such as a silicon substrate or a quartz substrate, can be used.

The photosensitive layer containing the sublimable organometallic complex and the silicon-based polymer compound can be formed, for example, by using the metal oxide thin film pattern forming composition of the present invention. Here, the composition for pattern formation of the present invention will be described.

The sublimable organometallic complex that can be incorporated in the composition of the present invention is not particularly limited with respect to the structure of the ligand and the type of the central metal.
It is desirable that the sublimation be performed at a heating temperature of about 200 ° C. to about 200 ° C. Further, it is preferable that the material be stable in the air and the decomposition reaction does not proceed simultaneously at the sublimation temperature.

Specifically, examples of the sublimable organometallic complex include β-diketone complexes such as an acetylacetone complex. The following complexes are suitably used since they have appropriate sublimability. Can be Al (AA) ₃ ,
Be (AA) ₂ , Ca (AA) ₂ , Cd (AA) ₂ , C
o (AA) ₃ , Cr (AA) ₃ , Cu (AA) ₂ , Eu
(AA) ₃ , Fe (AA) ₃ , Ga (AA) ₃ , In
(AA) ₃ , La (AA) ₃ , Mg (AA) ₂ , Mn
(AA) ₂ , Pb (AA) ₂ , Pt (AA) ₂ , Rh
(AA) ₃ , Ru (AA) ₃ , Sc (AA) ₃ , Th
(AA) _{4 ,} UO ₂ (AA) ₂ , Zn (AA) ₂ , and Zr (AA) ₄ . AA represents an acetylacetonate ligand.

In these acetylacetonato complexes, a trifluoropropyl group may be introduced instead of a terminal methyl group. Among the above-mentioned complexes, Al (AA)
₃ , In (AA) ₃ , La (AA) ₃ , Mg (AA)
₂ , Th (AA) ₄ and Zr (AA) ₄ are particularly preferred because of their excellent sublimability.

The sublimable organometallic complex can be appropriately selected and used depending on the combination with the silicon-based polymer compound and the application. When the present invention is applied to a high-contrast pattern, for example, an optical waveguide, it is desired to increase the difference in refractive index between an exposed portion and an unexposed portion. for that purpose,
As the metal species of the sublimable organometallic complex, the difference between the refractive index when the metal species forms a metal oxide alone and the refractive index of silicon oxide is preferably as large as possible.

The content of the sublimable organometallic complex in the composition for pattern formation of the present invention is not particularly limited. However, if the content is too low, the exposed and unexposed portions of the photosensitive layer after exposure will be different. A sufficient refractive index difference cannot be obtained. on the other hand,
If the content is too large, the sublimable organometallic complex and the silicon-based polymer compound may undergo phase separation and become non-uniform. Such non-uniformity, for example, when used in an optical waveguide, significantly degrades the optical characteristics. Also, when the present invention is applied to a surface imaging method, the resolution of a lithographic pattern is extremely reduced. Generally, the content of the sublimable organometallic complex is preferably 1 to 50%, more preferably 5 to 15%, based on the silicon-based polymer compound. However, the present invention is not limited to the case where the present invention is applied to the formation of a fine metal wiring pattern. Since the adhesion between the metal oxide thin film serving as the metal wiring base and the metal wiring pattern can be improved, it is desirable that the sublimable organometallic complex and the matrix such as a silicon-based polymer compound have a certain degree of phase separation. It is. For phase separation, the content of the sublimable organometallic complex is preferably about 1 to 1000%, more preferably 50 to 200%, based on a matrix component such as a silicon-based polymer compound.

Examples of the silicon-based polymer that can be contained in the composition for pattern formation of the present invention include an inorganic or organic silicon-based polymer compound and a silicon-based cluster.

Examples of the inorganic or organosilicon polymer compound include polysilanes, polysiloxanes, and polysilazanes. The molecular weight is not particularly limited, but is preferably from 500 to 5,000,000. And more preferably 10,000 to 1,000,000. If it is less than 500, the film-forming properties are not sufficient, and there is a possibility that it will be decomposed and volatilized. On the other hand, if it exceeds 5,000,000, the solubility in a solvent may be deteriorated during coating. The main chain of polysilanes and polysiloxanes is linear, branched, ladder-like,
It may be a dendrimer. However, in order to smoothly perform the sublimation of the sublimable organometallic complex, the main chain of the polysilane is preferably linear or dendrimer,
A good pattern can be formed with a higher contrast than that of a network. Further, polysilanes are oxidized at the time of exposure or heating and expand in volume. Since the volume shrinkage caused by the three-dimensional cross-linking occurring at the same time is offset, the occurrence of pattern distortion and cracks due to the volume change is suppressed, and a good pattern can be formed.

In particular, polysilanes and polysiloxanes having an alkoxy group in the side chain can reduce the amount of organic groups remaining in the film, and are effective in improving the heat resistance of the film. Further, when the present invention is applied to an optical waveguide, it is possible to reduce the propagation loss. Examples of the polysilanes and polysiloxanes having an alkoxy group in the side chain include polysilanes having repeating units represented by the following general formulas (I) and (II), and polysilanes having the following general formula (III)
And polysiloxanes having repeating units represented by (IV).

[0025]

Embedded image (In the above general formulas (I) and (II), R ¹ and R ² are selected from a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms, an aryl group, an aralkyl group,
They may be the same or different. )

[0026]

Embedded image (In the above general formulas (III) and (IV), R ³ and R ⁴ are
It is selected from a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms, an aryl group, and an aralkyl group, and may be the same or different. Examples of the unsubstituted alkyl group that can be introduced as R ^{1 to} R ^{4 in the} general formulas (I) to (IV) include a methyl group, an ethyl group, an isopropyl group, a tertiary butyl group,
Examples include an isobutyl group, a normal butyl group, and a hexyl group.

Examples of the substituent which can be introduced into these alkyl groups to form a substituted alkyl group include, for example, a trifluoromethyl group, a hydroxyl group, an alkoxy group, a carbonyl group,
Examples include a cyano group and a nitro group.

Further, examples of the unsubstituted aryl group include a phenyl group and a naphthyl group, and examples of the unsubstituted aralkyl group include a phenylethyl group and a phenylpropyl group.

The above-mentioned substituents can be introduced into such unsubstituted aryl groups and aralkyl groups. Further, since polysilanes or polysiloxanes having a hydrogen atom as a side chain are oxidized and cross-linked by heating, the amount of organic groups remaining can be reduced.

As the silicon-based cluster, for example, a cage-like polysiloxane such as silsesquioxane is used. Although the molecular weight of the cluster is not particularly limited,
It is preferably from 300 to 3,000, and from 400 to
More preferably, it is 1,000. If it is less than 300, the film formability is not sufficient, and the sublimable organometallic complex may volatilize when sublimated. On the other hand, 3,
If it exceeds 000, applicability and solvent solubility may be deteriorated.

Incidentally, the composition of the present invention may further contain a photoacid generator or a photobase generator in addition to the above-mentioned components. The photoacid generator is a compound that generates an acid upon irradiation with light, and examples thereof include a triphenylsulfonium salt such as triphenylsulfonium triflate and a naphthalimidyl salt such as naphthalimidyl camphorsulfonate. When the photoacid generator is blended, the blending amount is preferably about 0.1 to 5% based on the silicon-based polymer compound.

The photobase generator is a compound capable of generating a base upon irradiation with light, and is, for example, manufactured by Midori Kagaku Co., Ltd. having an orthonitrophenylmethyl group (trade name: NBC-
Photobase generators such as 1) are mentioned. When a photobase generator is blended, the blending amount is preferably about 0.1 to 5% based on the silicon-based polymer compound.

The composition for pattern formation of the present invention is prepared by mixing a silicon-based polymer compound with a sublimable organometallic complex at a predetermined ratio, and adding a photoacid generator, if necessary, to ethyl lactate, ethyl acetate. , PGMEA and the like, and dissolved in a solvent such as xylene, toluene, anisole, tetrahydrofuran, and methylene chloride, and used as a solution. This solution is applied on a substrate by a dipping method, a spin coating method, a doctor blade method, a solvent casting method, or the like to form a coating film.
The solvent is removed by heating at about 0 to 150 ° C. for about 0.5 to 5 minutes to form a photosensitive layer. The thickness of the photosensitive layer can be appropriately determined according to the concentration of the coating solution, the coating conditions, the application, and the like, and can be, for example, about 0.1 to 10 μm.

Alternatively, the photosensitive layer may be formed on a substrate by co-evaporating the above-described sublimable organometallic complex and a silicon-based polymer compound. In the method for forming a metal oxide thin film pattern according to the present invention, as described above, a process of irradiating a predetermined region of the photosensitive layer formed on the base material with light, followed by heating and drying is performed.

Now, the pattern forming method of the present invention will be described with reference to the drawings. FIG. 1 is a process sectional view schematically illustrating an example of a method for forming a metal oxide thin film pattern according to the present invention.

First, as shown in FIG. 1A, a photosensitive layer 2 formed on a substrate 1 is irradiated with exposure light 4 through a mask 3 having a predetermined pattern, for example, to perform pattern exposure. . The pattern exposure may be performed by directly scanning the photosensitive layer 2 with a laser light source or the like without using a mask.

As the light source for irradiating the exposure light 4, any light source can be used as long as it can sensitize the photosensitive layer 2. In other words, the light 4 used for exposure is one that decomposes or modifies the sublimable organometallic complex contained in the photosensitive layer 2 to eliminate or suppress sublimability, or a silicon-based polymer compound or a photosensitive material added separately. Any agent may be used as long as it causes a photoreaction in the agent and the photoreaction triggers to decompose or modify the sublimable organometallic complex to eliminate or suppress the sublimability. Specifically, an electron beam or the like can be used as the exposure light 4. Further, by controlling the amount of exposure of the exposure light 4 and providing a slope of the amount of exposure in the surface of the photosensitive layer or in the film thickness direction, a GI optical waveguide can be formed. Furthermore, a photonic band or an interference mirror may be formed by forming interference fringes in the photosensitive layer 2 by utilizing interference of a plurality of exposure beams.

If light having an absorption wavelength of the sublimable organometallic complex is used as the exposure light 4, this complex can be directly decomposed by exposure. For example, Al (AA) ₃ is 280 nm
It shows an absorption with a peak near, and Zr (AA) ₃ is 30
To show absorption having a peak near 0 nm, 300 nm
By performing pattern exposure by irradiating nearby ultraviolet light, the metal complex in the exposed portion can be decomposed. Also,
For example, when a metal complex having absorption in the visible light region such as Ru (AA) ₃ is used as a silicon-based polymer compound such as polysilane having strong absorption in an ultraviolet light region, the absorption of the silicon-based polymer compound is reduced. Without being hindered, the metal complex can be efficiently photolyzed.
Various sensitizers may be used to promote photodecomposition. Various sensitizing dyes can be used, and the amount thereof can be about 0.1 to 5% based on the silicon-based polymer compound.

In the pattern forming method of the present invention, the sublimable organometallic complex may be decomposed by exposure, and need not necessarily be directly decomposed by exposure as described above. By irradiating light, first, the silicon-based polymer compound and other photosensitive additives undergo a photoreaction to generate a photoreaction product, and the photoreaction product reacts with the above-described sublimable organometallic complex to form a complex. May be caused. For example, A
An acetylacetonato complex such as l (AA) ₃ causes a ligand exchange reaction by a hydroxyl group such as a silanol group or a phenolic hydroxyl group. Therefore, if such a hydroxyl group is used as a silicon-based polymer compound or a photosensitive additive as a result of a photoreaction by exposure to light, the hydroxyl group satisfactorily decomposes the sublimable organometallic complex and loses its sublimability. Can be done.

For example, polysilanes generate silanol groups by photo-oxidation, and hydro groups of polysilanes and polysiloxanes efficiently generate silanol groups by a photoreaction. Similarly, an alkoxy group introduced into a side chain of polysilanes or polysiloxanes generates a silanol group under heating or in the presence of an acid catalyst or the like. in this case,
As the acid catalyst or the like, the above-described photoacid generator or the like is used.

The polysilanes capable of eliminating the sublimability of the sublimable organometallic complex by such a mechanism include, for example, polydiisopropoxysilane, polyditertiarybutoxysilane, polyisopropoxymethylsilane, polytertiarybutoxymethylsilane, and polytertiarybutoxymethylsilane. Examples include tertiary butoxy silane, polymethyl silane, and polyphenyl silane, and polysiloxanes include polydiisopropoxy siloxane, polyditertiary butoxy siloxane, polyisopropoxy methyl siloxane, poly tertiary butoxy methyl siloxane, and poly tertiary siloxane. Butoxysiloxane, polymethylsiloxane, and polyphenylsiloxane.

Examples of the photosensitive additive for eliminating the sublimability of the sublimable organometallic complex by the mechanism described above include, for example, a photoacid generator and a phenol derivative such as tertiary butoxybenzene or a silanol such as isopropoxydiphenylsilane. And a mixture with a derivative.
When such a photosensitive additive is blended, it is desired that the blending amount is about 1 to 5% based on the silicon-based polymer compound.

The polysilanes and polysiloxanes having a tertiary butoxy group in the side chain are preferably used in combination with a latent catalyst such as a photoacid generator. When the organic group remains, the propagation loss may increase. However, the organic group is effective in producing a thick film, for example, because it prevents film shrinkage and cracking. In such a case, by using a fluorinated organic group, an increase in propagation loss can be suppressed to some extent. For similar reasons,
When an organic polymer such as polyimide is added for the purpose of improving film forming properties, it is desirable to use fluorine or a fluorinated compound such as polyimide.

By performing the pattern exposure as described above, in the exposed portion of the photosensitive layer, the sublimable organometallic complex is denatured to form a latent image on the photosensitive layer. That is, the sublimability of the sublimable organometallic complex is reduced in the exposed portion of the photosensitive layer, and in some cases, the sublimability in the exposed portion disappears.

By heating and drying the photosensitive layer 2 on which the latent image has been formed in this manner, the sublimable organometallic complex 5 in the unexposed portion 2b sublimates as shown in FIG. Removed from The heating and drying here is preferably determined in accordance with the properties of the sublimable organometallic complex, but is generally set to be higher than the sublimation temperature and lower than the decomposition temperature, and is preferably performed for about 1 minute to 5 hours, preferably 5 minutes. Min ~ 1
It is more preferable to carry out for about an hour. In the heating and drying, it is necessary to sublimate the sublimable organometallic complex without thermal decomposition or the like. Therefore, it is most preferable to heat and dry under a vacuum condition of about 1 torr or less so that the sublimation temperature is equal to or lower than the thermal decomposition temperature of the complex.

If a metal complex maintaining sublimability remains in the exposed portion 2a of the photosensitive layer, it is removed in the same manner. After that, if necessary, the entire surface of the photosensitive layer 2 is exposed to an exposure light source or an ultraviolet light source or the like, or a process such as heating at about 200 to 500 ° C. is performed.
The photosensitive layer may be mineralized as shown in (c). As a result, the decomposition product of the complex can be satisfactorily fixed to the matrix composed of the silicon-based polymer compound, or the silicon-based polymer compound matrix can be mineralized to improve the optical characteristics. For example, when polysilanes are used as the silicon-based polymer compound matrix, the entire surface is exposed and heated and dried, whereby the mineralization into a structure similar to SiO ₂ progresses.

By performing this step, the matrix in which the sublimable organometallic complex is dispersed becomes a nonporous dense resin film, so that a fine pattern with good processing accuracy can be formed.

As described above, by using the pattern forming method of the present invention, a pattern in which a silicon oxide thin film is doped with another metal element can be easily formed. When a metal oxide thin film formed in a pattern is subjected to plasma etching by an RIE process, the pattern can be used as an etching mask because the etching resistance varies depending on the type of metal contained. In this manner, the thin film to be processed provided under the pattern can be etched into a positive or negative image according to the formed pattern, and can be applied to a surface imaging method used for semiconductor fine processing.

FIG. 2 is a process sectional view schematically showing an example of such a method. First, as shown in FIG. 2A, a thin film (a thin film to be processed) 6 to be subjected to fine processing and the above-described photosensitive layer 2 are sequentially formed on a substrate 1.
Pattern exposure is performed by irradiating exposure light 4 via a mask 3 having a predetermined pattern. The material of the thin film 6 to be processed is not particularly limited, and can be formed to a thickness of about 0.1 to 10 μm by using, for example, a spin coating method, a dip coating method, a CVD method, and a sputtering method. Next, a latent image of a pattern is formed on the photosensitive layer 2 on the thin film 6 to be processed by performing heat drying and post-processing as necessary. Thereafter, the photosensitive layer 2 on which the latent image is formed is used as an etching mask to perform etching with an appropriate etching method as shown in FIG. Thus, a processed thin film 6a is obtained. As an etching method, a dry etching method is preferable in terms of excellent processing accuracy, and an anisotropic dry etching method is more preferable.

Alternatively, a fine metal wiring pattern can be formed using the metal oxide thin film pattern formed by the pattern forming method of the present invention. The metal species contained in the photosensitive layer is Pd, Pt, Rh, or R.
In the case of u, since it has a catalytic action of electroless plating,
A metal wiring pattern can be formed as follows. That is, by immersing a pattern composed of a portion containing these metal species and a portion not containing these metal species in the silicon oxide thin film as shown in FIG. In the site where it is contained,
The surface of the silicon oxide thin film is electrolessly plated using the metal species as a catalyst. In this case, any plating bath may be used as long as electroless plating proceeds according to the above-described metal species. On the other hand, the metal species is not contained,
Alternatively, very few portions are not subjected to electroless plating, so that a metal wiring pattern 9 as shown in FIG. 3 can be formed. When forming a metal wiring pattern in this way, the silicon oxide thin film does not necessarily need to be mineralized.

When the wiring pattern is not very fine, instead of applying a mixed solution of a silicon-based polymer compound and a sublimable organometallic complex to form a photosensitive layer, fine particles of the silicon-based polymer compound are used. To form a porous membrane,
The porous membrane may be used by impregnating it with a solution of a sublimable organometallic complex and adsorbing it. In addition, metal oxide fine particles can be used as such fine particles.

According to the present invention, as described above, it is possible to easily form a metal oxide thin film pattern such as a fine refractive index pattern having a small propagation loss and excellent heat resistance.

[0053]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. The following examples are for the purpose of specifically explaining, and do not limit the embodiments and the scope of the present invention. (Embodiment 1) In this embodiment, a photomask having a two-branch waveguide pattern with an optical waveguide width of 20 μm and a pitch of 250 μm of branch waveguides is used, and the method of the present invention is applied to 20 ×.
A two-branch optical waveguide device having a rectangular cross section of 1 μm was manufactured.

First, Zr as a sublimable organometallic complex
(AA) ₄ was mixed with polydiisopropoxysiloxane as a silicon-based polymer compound at a ratio of 10 wt%, and this mixture was dissolved in toluene to prepare a toluene solution. The obtained toluene solution was applied on a glass substrate by a spin coating method, and the solvent was removed by heating at 100 ° C. for 1 minute to form a photosensitive layer having a thickness of about 1 μm.

The obtained photosensitive layer was irradiated with ultraviolet light having a wavelength of 300 nm using the above-described photomask (irradiation amount: 1 W /
cm ² ) to form a latent image. After the irradiation, it was confirmed that absorption near 300 nm caused by Zr (AA) ₄ disappeared in the exposed portion of the photosensitive layer.

The photosensitive layer on which the latent image was formed was heated at 150.degree.
Vacuum heating and drying were performed at 0 ^-2 torr for 1 hour. Next, the entire surface is exposed to ultraviolet light having a wavelength of 300 nm (irradiation amount: 1 W
/ Cm ² ), and further heated at 450 ° C. for 30 minutes to form a core layer. The upper surface of the obtained core layer was spin-coated with a polysilazane solution, and heated at 450 ° C. for 30 minutes to form an upper clad layer to obtain an optical waveguide device.

In the manufactured optical waveguide device, the difference in refractive index between the exposed portion and the unexposed portion was 3.2%. Wavelength 67
The transmission loss at 0 nm shows a relatively good value of 0.06 dB / cm, and since the characteristics hardly change even after heating at 450 ° C. for 5 hours in air, it has sufficient heat resistance. I knew it was there. Furthermore, it was confirmed that the difference in the coefficient of thermal expansion between the waveguide pattern and the substrate was also small. Example 2 An optical waveguide was manufactured in the same manner as in Example 1 except that polydiisopropoxysilane was used as the silicon-based polymer compound.

In the manufactured optical waveguide device, the difference in refractive index between the exposed portion and the unexposed portion was 3.4%. Wavelength 67
The transmission loss at 0 nm shows a relatively good value of 0.07 dB / cm, and there is almost no change in the characteristics even after heating at 450 ° C. for 5 hours in air. I knew it was there. Furthermore, it was confirmed that the difference in the coefficient of thermal expansion between the waveguide pattern and the substrate was also small. Example 3 As a sublimable organometallic complex, Zr (AA) was used.
Al (AA) ₃ , In (AA) instead of _4
3 , La (AA) ₃ , Mg (AA) ₂ , and Th (A
A) An optical waveguide device was produced in the same manner as in Example 1 except that ₄ was used.

The produced optical waveguide device has a difference in refractive index between the exposed portion and the unexposed portion of 3% or more, and the transmission loss is 67 nm.
0.1 dB at 0 nm and 1.3 μm
/ Cm or less. In addition, since there was almost no change in the characteristics even after heating at 450 ° C. for 5 hours in air, it was found that the composition had sufficient heat resistance. Furthermore, it was confirmed that the difference in the coefficient of thermal expansion between the waveguide pattern and the substrate was also small. Example 4 As a sublimable organometallic complex, Zr (AA) was used.
₄ instead of In (AA) ₃ and La (AA) respectively
₃ , an optical waveguide device was manufactured in the same manner as in Example 2 except that Mg (AA) ₂ and Th (AA) ₄ were used.

The produced optical waveguide device had a difference in refractive index between the exposed portion and the unexposed portion of 3% or more, and the transmission loss was 67 nm.
0.1 dB at 0 nm and 1.3 μm
/ Cm or less. In addition, since there was almost no change in the characteristics even after heating at 450 ° C. for 5 hours in air, it was found that the composition had sufficient heat resistance. Furthermore, it was confirmed that the difference in the coefficient of thermal expansion between the waveguide pattern and the substrate was also small. Example 5 Zr (AA) ₄ as a sublimable organometallic complex
An optical waveguide device was manufactured in the same manner as in Example 1 except that Al (AA) ₃ was used instead of.

The manufactured optical waveguide device has a difference in refractive index between the exposed portion and the unexposed portion of 1% or more, and has a transmission loss of 67 nm.
0.1 dB at 0 nm and 1.3 μm
/ Cm or less. In addition, since there was almost no change in the characteristics even after heating at 450 ° C. for 5 hours in air, it was found that the composition had sufficient heat resistance. Furthermore, it was confirmed that the difference in the coefficient of thermal expansion between the waveguide pattern and the substrate was also small. (Embodiment 6) In this embodiment, a fine refractive index distribution pattern in the film thickness direction was formed.

Al (AA) as sublimable organometallic complex
₃ was mixed with polydiisopropoxysiloxane as a silicon-based polymer compound at a ratio of 10 wt%, and this mixture was dissolved in toluene to prepare a toluene solution. The obtained toluene solution was applied on a glass substrate by a spin coating method, and the solvent was removed by heating at 100 ° C. for about 1 minute to form a photosensitive layer having a thickness of about 5 μm.

A laser beam having a wavelength of 266 nm was used as a light source, and biaxial light beams were exposed to the substrate from both sides of the photosensitive layer at an incident angle of 60 ° and a crossing angle of the beam optical axis of 120 °. The irradiation spot diameter is about 100
μm.

After the exposure, the photosensitive layer is exposed at 150 °, 10 ⁻² to
Vacuum heating and drying were performed at rr for 1 hour. After drying by heating under vacuum, the entire surface is exposed to ultraviolet light having a wavelength of 300 nm (irradiation amount: 1 W / cm
² ) and further heated at 450 ° C. for 30 minutes.

The depth profile of the aluminum element at the irradiation site of the obtained film was measured by XPS measurement. As a result, a periodic change in the aluminum element content was observed in the thickness direction of the irradiated portion, and it was found that a refractive index distribution could be formed also in the thickness direction of the photosensitive layer. (Embodiment 7) In this embodiment, a fine pattern was formed by a surface imaging method.

Pt (AA) as Sublimable Organometallic Complex
₂ was mixed with polydiisopropoxysiloxane as a silicon-based polymer compound at a ratio of 10 wt%, and this mixture was dissolved in toluene to prepare a toluene solution.

On the other hand, a crosslinked novolak resin film having a thickness of 0.7 μm is formed on a silicon substrate, and the above-mentioned toluene solution is applied on the resin film by spin coating.
The solvent was removed by heating at 100 ° C. for about 1 minute to produce a photosensitive layer having a thickness of about 0.1 μm.

Using a photomask having a line and space pattern of 0.5 μm, a wavelength of 300
The latent image was formed by irradiating ultraviolet light of nm (irradiation amount: 1 W / cm ² ).

The photosensitive layer on which the latent image was formed was heated at 150.degree.
The pattern was formed by drying by heating under vacuum at 0 ^-2 torr for 1 hour. The patterned thin film was dry-etched by reactive ion etching using chlorine gas to finely process the novolak resin film. As a result, the novolak resin film could be patterned with a line and space of about 0.5 μm. (Embodiment 8) In this embodiment, a fine metal wiring pattern was formed.

Pt (AA) as Sublimable Organometallic Complex
₂ was mixed with polydiisopropoxysiloxane as a silicon-based polymer compound at a ratio of 10 wt%, and this mixture was dissolved in toluene to prepare a toluene solution. The obtained toluene solution was applied on a glass substrate by a spin coating method, and the solvent was removed by heating at 100 ° C. for about 1 minute to produce a photosensitive layer having a thickness of about 1 μm.

Using a photomask having a line and space pattern of 5 μm, a wavelength of 300 nm was applied to the prepared photosensitive layer.
(Irradiation amount: 1 W / cm ² ) to form a latent image.

The photosensitive layer having the latent image formed thereon was heated at 150.degree.
The pattern was formed by drying by heating under vacuum at 0 ^-2 torr for 1 hour. The pattern-formed thin film was immersed in a nickel electroless plating bath to deposit a 1 μm-thick nickel thin film on the pattern portion containing Pt. As a result, a good nickel electrode pattern was formed. Example 9 First, silica fine particles (average particle diameter of about 20 nm) were coated on a glass substrate to a thickness of 1 μm by a squeegee printing method.
m to form a porous film, and this porous film is coated with Pt
(AA) ₂ was adsorbed to form a photosensitive layer. When a pattern was formed in the same manner as in Example 8 except that the thus obtained photosensitive layer was used, a good nickel electrode pattern was formed.

[0073]

As described above, according to the present invention, a metal oxide which can form a refractive index distribution of an inorganic optical waveguide, a photonic band, an interference mirror, etc., having a small propagation loss and excellent heat resistance. Provided are a method for easily forming an object thin film pattern and a pattern forming composition used for the method.

The present invention can be very suitably used for a surface imaging method used for a semiconductor fine processing process and for forming a metal wiring pattern, and the industrial value thereof is enormous.

[Brief description of the drawings]

FIG. 1 is a process sectional view schematically showing an example of a pattern forming method of the present invention.

FIG. 2 is a process sectional view schematically showing another example of the pattern forming method of the present invention.

FIG. 3 is a cross-sectional view schematically illustrating an example of a metal wiring pattern formed by the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Photosensitive layer 2a ... Exposed part 2b ... Unexposed part 3 ... Mask 4 ... Exposure light 5 ... Sublimable organometallic complex 6 ... Thin film to be processed 7 ... Plasma 9 ... Metal wiring pattern

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shuji Hayase 1st address, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa F-term in Toshiba R & D Center (reference) 2H025 AA10 AB14 AB16 AB17 AB20 AC01 AD01 CB32 CB33 CC20 FA12 FA14 FA28 2H047 AA03 EE02 EE04 EE05 EE21 EE22 EE24 GG05 2H096 AA25 AA26 BA01 BA20 EA02 FA01 HA27 HA30

Claims (4)

[Claims] A step of forming a photosensitive layer containing a sublimable organometallic complex and a silicon-based polymer compound on a substrate, selectively exposing a predetermined region of the photosensitive layer to a latent image of a thin film pattern; A method for forming a metal oxide thin film pattern, comprising: a step of forming an image; and a step of heating and drying the photosensitive layer on which the latent image of the thin film pattern is formed to remove an unexposed sublimable organometallic complex. 2. The method according to claim 1, wherein the sublimable organometallic complex is an acetylacetone complex derivative. 3. A composition for forming a metal oxide thin film pattern, comprising a sublimable organometallic complex and a silicon-based polymer compound. 4. A step of forming a photosensitive layer containing a sublimable organometallic complex on a substrate, a step of selectively exposing a predetermined region of the photosensitive layer to form a latent image of a thin film pattern, Heating and drying the photosensitive layer on which the latent image of the thin film pattern is formed, removing the sublimable organometallic complex in the unexposed portion,
And forming a metal fine pattern on the exposed portion of the photosensitive layer after the heating and drying.