JPH05275831A - Production of conductive pattern - Google Patents

Abstract

PURPOSE:To form a fine submicron conductive pattern not only on a flat plane but also on an edge, a side and a curved part without using a mask by patterning a base layer of organic fatty acid LB (Langmuir-Blodgett) film, laminating a conductive precursor and permitting topochemical polymerization. CONSTITUTION:An extremely thin film is manufactured by laminating monomolecular films layer by layer. After patterning an organic fatty acid film manufactured by LB method, a precursor that becomes conductive after polymerization is laminated on the organic fatty acid by LB method, the precursor part on the organic fatty acid is selectively polymerized by applying light so as to allow conductivity and a conductive pattern is manufactured. The inclination of the molecular chain of a reactive precursor molecular LB film 303 formed on the organic fatty acid LB film 302 formed on a board 301 and the inclination of the molecular chain of a non-reactive precursor molecular LB film 304 formed on a part whereupon the organic fatty acid LB film is not present are different and polymerization is allowed only for the inclination of the former.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor integrated circuit or a printed circuit board used for electronic parts, and more particularly to a method for manufacturing a fine conductive pattern.

[0002]

2. Description of the Related Art In recent years, conductive printed circuit boards used for wiring between electronic parts have been increasingly densified and miniaturized in combination with the improvement of element density.
A conventional method for manufacturing a printed circuit board is as follows.

A metal thin film of copper or aluminum is formed on a resin such as polyimide or glass epoxy by plating, vapor deposition and spattering. In this case, the thickness of the metal film is about ten and several μm. In order to form a fine conductive pattern on this resin plate, a photo etching method is usually used. In this method, a photoresist that is either cured (negative type) or decomposed (positive type) by irradiation with ultraviolet rays is coated on the metal film by means selected from spin coating, dipping, and the like.

After the photoresist is dried to such an extent that it does not come into contact with the mask even if it is in close contact with the mask, a mask having a light-shielding pattern is in close contact with the substrate and is irradiated with ultraviolet rays. This is dissolved and developed with an appropriate solvent to wash away the resist portion other than the conductive pattern. After that, the metal film is etched to dissolve and remove the portion other than the desired pattern. The remaining resist is peeled off to form a conductive pattern.

The coating method is selected from spin coating, dipping, printing, etc. according to the purpose of use. For patterning, it is necessary to uniformly coat the conductive metal film with a photoresist having a thickness equal to or smaller than the intended line width. As the line width becomes finer, the photoresist needs to be thinned accordingly.

Therefore, under such a limitation, it is extremely difficult to uniformly coat the side surface and the end surface of the substrate or the curved portion having a constant curvature. Therefore, it is impossible to make fine wiring on the back side through the side surface with one substrate.

Needless to say, it is not possible to obtain a fine pattern by uniformly coating a photoresist with a thickness of submicron or less by a printing method other than spin coating. Therefore, under the present circumstances, it is impossible to pattern a conductive pattern having a line width of about submicron.

[0008]

The present invention enables the patterning of a conductive pattern having a line width on the order of submicrons, and at the same time, even for a side surface or an end surface of a substrate or a curved portion having a constant curvature, It is to provide a method that enables fine wiring.

[0009]

In order to solve the above problems, the present invention is directed to a method of patterning an organic fatty acid film formed by the Langmuir-Blodgett method, and then producing a precursor which exhibits conductivity when polymerized by the organic fatty acid. A conductive pattern is produced by laminating the precursors on the organic fatty acid by light irradiation and selectively polymerizing the precursor portion on the organic fatty acid to give conductivity.

The Langmuir-Blodgett method (hereinafter simply referred to as the LB method) is a method for producing an ultrathin film in which monomolecular films are laminated one by one. This is because an amphipathic organic substance is dissolved in a solvent having a low boiling point, which is lighter than the specific gravity of water and insoluble in water, and then spreads on the water surface (203). As shown in FIG. 2, this causes the solvent to evaporate rapidly, and the hydrophilic group (201) of the organic substance floats on the water surface (203) with the hydrophilic group (201) facing downward and the hydrophobic group (202) facing upward (air side). .. Barrier (20
When 4) is used and a certain pressure is applied to agglomerate the molecules, a two-dimensional solid film of an amphipathic organic substance can be formed (see FIG. 3).

An ultrathin film of an organic material can be formed by copying this state layer by layer by the vertical dipping method in which the substrate (205) is vertically moved up and down so that it is pressed against the substrate (205) (see FIG. 4). .. As another lamination method, a horizontal attachment method in which a substrate is brought into close contact with the water surface and the film is copied in the state shown in FIG.

There is an advantage that an ultrathin film of an organic substance can be formed not only on a flat substrate but also on a narrow portion such as a side surface of the substrate or a curved surface having a constant curvature by any means or by slight modification. ..

In the present invention, various amphipathic organic substances are treated by the LB method.
Based on the following findings found in the process of stacking by
There is. It is a fatty acid (CH
₃(CH₂) _nArachidic acid (n = 18), a type of C00H)
~ When two layers are accumulated and when arachidic acid is not accumulated
Polydiacetyl which has conductivity when polymerized
An amphipathic precursor of len (Chemical Formula 1) was laminated.

[0014]

[Chemical 1]

This was irradiated with ultraviolet light to examine whether the precursor was polymerized. As a result, it was revealed that the polymerization reaction of the precursor proceeded only when the arachidic acid was laminated to produce a crystallized polydiacetylene film.
That is, the underlying organic fatty acid film was essential for the progress of the polymerization reaction.

The reason for this is that in order for the polymerization reaction of the precursor to proceed, it is necessary for the reactive functional groups of the precursor molecule to have a certain regular orientation so as to approach each other. There is. This state is shown in FIG.
01) LB film of organic fatty acid formed on (302)
Reactive precursor molecule LB film (30
3) The inclination of the molecular chain and the precursor molecule LB film (3
It is considered that the inclination of the molecular chain of 04) is different, and the polymerization reaction proceeds only in the former inclination.

This is because the polymerization of the precursor belongs to a so-called topochemical reaction (a chemical reaction that may or may not occur depending on the steric arrangement of molecules).

This finding suggests that if the underlying organic fatty acid LB film is patterned and then a conductive precursor is laminated to cause topochemical polymerization, only the portion corresponding to the underlying pattern is polymerized. Since the non-polymerized portion can be washed away with a suitable solvent, a conductive pattern is formed on the substrate.

As a means for forming a fatty acid pattern on the substrate, it is possible to irradiate an unnecessary portion with an electron beam or excimer laser light having a short wavelength in a vacuum to fly it. Alternatively, a mask may be applied and plasma treatment may be performed to remove unnecessary portions. However, with this method, the pattern is limited by the accuracy of the mask and there is a limit to the miniaturization of the pattern. It is preferable to use the former beam to draw a very fine pattern.

According to these, it is possible to draw a line having a submicron line width. Further, the LB film can be laminated on the end surface where spin coating cannot be used, and patterning by beam or light irradiation is also possible.

The conductive pattern (103) on the substrate (101) thus obtained is shown in FIG. 1, but an insulating organic material film may be formed by the LB method to further protect the surface. The number of carbon atoms is n as an organic fatty acid that can be used as a base
Similar results were obtained with long-chain fatty acids of 17-23.

[0022]

The present invention makes good use of the Langmuir-Blodgett method and utilizes the properties of the topochemical reaction.
It is possible to form an extremely fine conductive pattern of sub-micron level not only on a plane without using a mask but also on an end face, a side face, or a curved portion where a pattern cannot be conventionally drawn.

[0023]

Example 1 A well-cleaned glass substrate or silicon wafer was exposed to the hexamethyldisilazane saturated vapor of (Chemical Formula 2) for a whole day and night for hydrophobic treatment.

[0024]

Embedded image [(CH ₃ ) ₃ Si] ₂ NH

First, arachidic acid was further transferred onto this substrate by a vertical dipping method at a constant film pressure of 30 dynes using an LB film manufacturing apparatus (NL-LB301-MWH, manufactured by Nippon Laser Electronics Co., Ltd.). Set this under the EB irradiation device,
The substrate was moved so that a desired conductive pattern was drawn, and unnecessary portions were removed. Then, the polydiacetylene precursor represented by the above (formula 1) was further laminated by the horizontal deposition method.

After that, the entire surface was irradiated with ultraviolet rays containing the photosensitive wavelength of the precursor for about 30 minutes. When observed under a polarizing microscope, the interference color was visible only in the part of the pattern where the underlying fatty acid remained, and the rest was in the dark field, indicating that the polymerization reaction proceeded only in the part where the interference color was visible. It was
After that, the substrate was washed by plasma ashing to form a conductive pattern of polydiacetylene on the substrate.

Precursor L kept at a film pressure of 30 dynes
The precursor film was laminated on the B film by pulling up the substrate from water. After that, irradiation with ultraviolet light and washing were performed to overlap the conductive patterns to form two layers. By repeating the above process 5 times, a polydiacetylene conductive pattern having a thickness of 10 layers was formed. The line width of polydiacetylene that can be produced by this method was 0.4 μm. The conductivity is approximately 0.05 Siemens.

<Embodiment 2> As the underlying fatty acid LB film,
Behenic acid with n = 20 was used. By repeating the same procedure as in Example 1, a polydiacetylene conductive pattern was obtained.

[0029]

According to the present invention, an extremely fine conductive pattern of the order of submicron is formed not only on a plane without using a mask but also on an end face, a side face or a curved portion where a pattern cannot be drawn conventionally. It is possible.

[0030]

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing a conductive pattern according to the present invention.

FIG. 2 is an explanatory view schematically showing a method of manufacturing an LB film.

FIG. 3 is an explanatory view schematically showing a method for manufacturing an LB film.

FIG. 4 is an explanatory view schematically showing a method of manufacturing an LB film.

FIG. 5 is an explanatory view schematically showing that the underlying organic fatty acid film affects the alignment state of the polymerizable precursor.

[Explanation of symbols]

 (101) Substrate (102) Organic fatty acid LB film (102) Polydiacetylene LB film (201) Hydrophilic group (202) Hydrophobic group (203) Water surface (204) Barrier (205) Substrate (301) Substrate (302) Stearin Acid LB film (303) Reactive precursor molecule LB film (304) Unreactable precursor molecule LB film

Claims (1)

[Claims] 1. An organic fatty acid film formed by the Langmuir-Blodgett method is patterned, and then a reactive precursor exhibiting conductivity by polymerization is laminated on the organic fatty acid by the Langmuir-Blodgett method, A method for producing a conductive pattern, which comprises selectively polymerizing a precursor portion on the organic fatty acid by irradiation to impart conductivity.