JP4277976B2 - Method for forming plating seed pattern and conductive film pattern - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plating seed pattern and a method for forming a conductive film pattern, and more particularly to a method for forming a fine plating seed pattern on a substrate by an inkjet method and a method for forming a conductive film pattern on the seed pattern. This method can be used in the electric and electronic fields for forming electrodes for PDPs and LCDs, forming conductive circuits on printed boards, and forming light shielding patterns.
[0002]
[Prior art]
In recent years, with the miniaturization of wiring, wiring formation by an inkjet (IJ) method has attracted attention as a promising technique from the viewpoint of cost reduction and environmental protection measures.
[0003]
In the field where a thick film is required when forming a wiring or the like made of a conductive film pattern by the IJ method, in order to increase the film thickness, a method of stacking films by repeating the number of IJ drawing is used. Rather than repeating drawing, forming a thick wiring film by plating leads to cost reduction. For this reason, a method has been proposed in which a catalyst made of fine particles of noble metal such as Pd is deposited on a substrate as a nucleus and electroless plating is performed by the action of this catalyst to form a conductive film pattern (see, for example, Patent Document 1). ). In this case, the polysilane solution is ejected into a predetermined pattern using an IJ apparatus, and the solvent is burned off to form a polysilane film pattern. Then, the oxidation-reduction reaction between a noble metal salt such as a Pd salt and polysilane is used. A catalyst of noble metal fine particles is deposited on the polysilane film pattern, and then a conductive film pattern is formed.
[0004]
[Patent Document 1]
JP 2001-230527 A (Claims etc.)
[0005]
[Problems to be solved by the invention]
However, in the method described in the above prior art, polysilane remains between the substrate and the plating film, and even though the polysilane has conductivity, the residual polysilane has the desired conductivity of the conductive film. There is a problem of adverse effects. Moreover, in order to apply a polysilane solution to IJ drawing, it is very difficult to solve problems such as adjusting the viscosity of the solution and controlling the volatility of the solvent. Furthermore, in this prior art, in order to form a catalyst that becomes the core of plating on the substrate, an extra step that polysilane that is not necessarily required must be performed by IJ drawing is required, and portions other than the pattern are required. A washing process for removing the catalyst adhering to the catalyst is also necessary. Thus, there is a problem that a waste liquid treatment is involved because two steps of polysilane film formation and catalyst deposition are necessary before forming the conductive film, and a cleaning step is also necessary. Furthermore, in this prior art, a Pd salt or the like is used for the precipitation of the catalyst. However, since this Pd salt is strongly alkaline, it may damage the nozzle head of the IJ apparatus.
[0006]
An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a plating seed pattern forming method and a conductive film pattern forming method that do not require a polysilane pattern forming step.
[0007]
[Means for Solving the Problems]
The inventors of the present invention have disclosed a dispersion in which ultrafine metal particles are dispersed in an independent state, that is, a metal that does not cause aggregation of ultrafine particles, maintains fluidity, and is excellent in ink-jet ink characteristics. The present inventors have found that the above-described problems of the prior art can be solved by an ink jet method using nano ink, which is an ultrafine particle independent dispersion, and have completed the present invention.
[0008]
Plating seed pattern forming method of the present invention, Cu, Ag, ultrafine particles of a metal selected from Au and Pd, see contains a dispersant and an organic solvent, nano ink (hereinafter viscosity of 3～20Cps, ultrafine metal particles (Also referred to as an independent dispersion), by direct drawing by an inkjet method, a seed line is drawn on a substrate having a surface roughness of Rmax = 20 to 500 nm while maintaining the substrate temperature at 60 to 100 ° C. The dispersing agent and the solvent are evaporated to form a plating seed pattern. Since polysilane is not used, it is possible to form a high-purity seed pattern for plating by a simple method without requiring a cleaning step and a waste liquid treatment step.
[0009]
The viscosity of the nano-ink is difficult to ensure the adhesion between the substrate exceeds 20 cps, also, since the viscosity of the nano-ink will spread the line width drawn is less than 3 cps, desired line by plating A width pattern cannot be formed.
The nano ink contains 0.1 to 15 wt%, preferably 0.1 to 10 wt% of ultrafine metal particles. If it is out of the range of 0.1 to 15 wt%, it is difficult to ensure adhesion with the substrate.
In the case of the present invention, since an organic solvent is used as the solvent of the nano ink, the viscosity and concentration can be freely adjusted. In order to reduce the content (concentration) and viscosity of the ultrafine metal particles, it may be thinned using the solvent itself. To increase the viscosity, a high-viscosity solvent such as α-terpineol can be mixed to obtain the desired content. Viscosity can be adjusted.
[0010]
It is preferable to use a substrate whose surface has been previously roughened as the substrate in order to achieve close contact between the substrate and the plating film. In this case, if the surface roughness is too large, it will hinder the refinement of the pattern of the plating film, and if the surface roughness is insufficient, the adhesion between the plating film and the substrate cannot be secured. The optimum value of roughness is Rmax = 20 to 500 nm. This roughening treatment method may be a chemical etching method, a liquid honing method, a sand blasting method, or the like.
[0011]
In the drawing in the plating seed pattern forming method of the present invention, it is preferable that the temperature of the substrate is maintained at 60 to 100 ° C. In the formation of a fine seed pattern, there is a method of hydrophobizing the substrate surface. However, there are cases where the drawing line width cannot be controlled only by the hydrophobizing process depending on the degree of surface roughness. In such a case, it is effective to heat the substrate to a predetermined temperature and perform drawing while maintaining the temperature. Outside this temperature range, the desired drawing line width cannot be achieved. For example, the line width of the pattern obtained by drawing while maintaining the substrate temperature at 100 ° C. is 1/5 to 1/14 compared to the line width obtained by drawing while maintaining the room temperature.
[0012]
The conductive film pattern forming method of the present invention is characterized in that after a plating seed pattern is formed by the above method, a conductive film pattern is formed on the seed pattern by electroless plating. Thus, a photolithography process is not required, the number of processes can be reduced, and a conductive film pattern having a desired line width and good conductivity can be provided. Moreover, the high adhesiveness with respect to the to-be-processed substrate of this electrically conductive film pattern can also be achieved.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The nano-ink, which is an independent dispersion of ultrafine metal particles used in the present invention, has ultrafine particles of metal selected from Cu, Ag, Au and Pd individually and uniformly dispersed to maintain fluidity. It is useful as an inkjet ink for forming a seed pattern.
[0014]
The ultrafine metal particles can be produced by, for example, a low vacuum gas evaporation method. According to this production method, ultrafine metal particles having a particle size of 100 nm or less, preferably 10 nm or less can be produced. . In order to be suitable for use as an ink for an ink jet printer using such ultrafine metal particles as a raw material, solvent replacement is performed in the final step (third step) as described below. In order to increase the dispersion stability of the ultrafine particles, a dispersant is added in a predetermined step. For this reason, the ultrafine metal particles are dispersed individually and uniformly, and a fluid state is maintained, thereby obtaining a nano ink suitable for the ink jet method.
[0015]
In the case of ink-jet ink, in order to realize ink supply stability, ink droplet formation flight stability, high-speed response of the printer head, etc., at a normal operation temperature (0 to 50 ° C.) It is required to have the following viscosity and surface tension. The nano ink used in the method of the present invention satisfies this ink characteristic.
[0016]
When producing the desired ultrafine metal particle independent dispersion using the ultrafine metal particles obtained by the low-vacuum gas evaporation method as the nano ink used in the method of the present invention, first, in the first step, in the vacuum chamber In addition, when the metal is evaporated under an atmosphere in which the pressure of the inert gas such as He is 10 Torr or less and the vapor of the evaporated metal is collected by cooling, one or more kinds of the first solvent are contained in the vacuum chamber. Steam is introduced, and the surface of the metal is brought into contact with the first solvent vapor at the stage of grain growth, and the resulting primary particles are dispersed in a colloidal form in the first solvent independently and uniformly. The first solvent is removed in the second step. The reason for removing the first solvent in this way is to remove by-products generated by the modification of the coexisting first solvent when the metal vapor evaporated in the first step is condensed. In addition, in order to produce such a dispersion when it is necessary to use an independent dispersion of ultrafine metal particles dispersed in a low-boiling solvent, water, an alcohol-based solvent, or the like that is difficult to use in the first step, depending on the use of the ink. But there is.
[0017]
In the second step, a second solvent, which is a low molecular weight polar solvent, is added to the dispersion obtained in the first step to precipitate the ultrafine metal particles contained in the dispersion, and the supernatant is allowed to stand. And the first solvent used in the first step is removed by decantation or the like. This second step is repeated a plurality of times to substantially remove the first solvent.
In the third step, a new third solvent is added to the precipitate obtained in the second step to perform solvent replacement, thereby obtaining a desired metal ultrafine particle independent dispersion. Thereby, an ultrafine metal particle independent dispersion in which ultrafine metal particles having a particle size of 100 nm or less are dispersed in an independent state is obtained.
In said case, a dispersing agent can be added at a 1st process and / or a 3rd process as needed. When added in the third step, a dispersant that does not dissolve in the solvent used in the first step can also be used.
[0018]
Although it does not specifically limit as a dispersing agent which can be used with the said manufacturing method, One or more things chosen from alkylamine, carboxylic acid amide, and aminocarboxylate are used. In particular, the alkylamine may be a primary to tertiary amine, or a monoamine, diamine, or triamine. An alkylamine having 4 to 20 carbon atoms in the main chain is preferable, and an alkylamine having 8 to 18 carbon atoms in the main chain is more preferable from the viewpoints of stability and handling properties. If the alkylamine has a main chain shorter than 4 carbon atoms, the basicity of the amine is too strong and the metal ultrafine particles tend to be corroded, and eventually the metal ultrafine particles are dissolved. In addition, when the number of carbon atoms of the alkylamine main chain is longer than 20, when the concentration of the metal ultrafine particle independent dispersion is increased, the viscosity of the dispersion rises and the handling property becomes slightly inferior. There is a problem that carbon tends to remain in the fired metal film and the specific resistance value increases. Moreover, although all series of alkylamines work effectively as a dispersant, primary alkylamines are preferably used from the viewpoints of stability and handling properties.
[0019]
Specific examples of the alkylamine include primary amines such as butylamine, octylamine, dodecylamine, hexadodecylamine, octadecylamine, cocoamine, tallowamine, hydrogenated tallowamine, oleylamine, laurylamine, and stearylamine. Secondary amines such as dicocoamine, dihydrogenated tallowamine, distearylamine and the like, and dodecyldimethylamine, didodecylmonomethylamine, tetradecyldimethylamine, octadecyldimethylamine, cocodimethylamine, dodecyltetradecyldimethylamine, And tertiary amines such as trioctylamine and the like, as well as naphthalenediamine, stearylpropylenediamine, octamethylenediamine, and nonanediamine There is an amine.
[0020]
Specific examples of the carboxylic acid amide and aminocarboxylic acid salt include, for example, stearic acid amide, palmitic acid amide, lauric acid lauryl amide, oleic acid amide, oleic acid diethanolamide, oleic acid lauryl amide, stearanilide, oleylaminoethylglycine. Etc.
One or more of these alkylamines, carboxylic acid amides, and aminocarboxylates can be used, thereby acting as a stable dispersant.
The content of the alkylamine is usually in the range of about 0.1 to 10% by weight, preferably 0.2 to 7% by weight, based on the weight of the ultrafine metal particles. When the content is less than 0.1% by weight, there is a problem that the ultrafine metal particles are not dispersed in an independent state, but aggregates thereof are generated, resulting in poor dispersion stability, and more than 10% by weight. And the viscosity of the obtained dispersion liquid becomes high, and there exists a problem that a gel-like thing is finally formed.
[0021]
As for the above solvents, it is necessary to select polar solvents such as water and alcohols and nonpolar hydrocarbon solvents in accordance with the properties of the substrate to be treated such as glass substrate, plastic substrate, ceramic substrate, etc. In addition, the conditions for selecting the solvent may be determined depending on the use of the obtained membrane.
For example, the first solvent is a solvent for producing ultrafine metal particles used in the gas evaporation method, and is a solvent having a relatively high boiling point so that the ultrafine metal particles can be easily liquefied when cooled and collected. is there. As the first solvent, a solvent containing one or more selected from alcohols having 5 or more carbon atoms, for example, terpineol, citronol, geraniol, phenethyl alcohol, etc., or organic esters, for example, benzyl acetate, stearin Any solvent containing at least one selected from ethyl acid, methyl oleate, ethyl phenylacetate, glycerides and the like may be used, and the solvent can be appropriately selected depending on the constituent elements of the metal ultrafine particles used or the use of the dispersion.
[0022]
The second solvent is not particularly limited as long as it can precipitate the ultrafine metal particles contained in the dispersion obtained in the first step, and extract and separate the first solvent. There are acetone and the like.
As the third solvent, a non-polar hydrocarbon having 6 to 20 carbon atoms in the main chain, water, an alcohol having a carbon number of 15 or less, and the like that are liquid at room temperature can be appropriately selected and used. In the case of non-polar hydrocarbons, if the carbon number is less than 6, drying is too early and there is a problem in handling the dispersion liquid. If the carbon number exceeds 20, the viscosity of the dispersion liquid is likely to increase, In addition, there is a problem that carbon tends to remain when firing. Also in the case of alcohol, when the number of carbons exceeds 15, the viscosity of the dispersion liquid tends to increase, and in the case of firing, there is a problem that carbon tends to remain.
[0023]
Examples of the third solvent include long-chain alkanes such as hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, octadecane, nonadecane, eicosane, and trimethylpentane, cyclohexane, cycloheptane, Cyclic alkanes such as cyclooctane, aromatic hydrocarbons such as benzene, toluene, xylene, trimethylbenzene, and dodecylbenzene, and alcohols such as hexanol, heptanol, octanol, decanol, cyclohexanol, and terpineol can be used. These solvents may be used alone or in the form of a mixed solvent. For example, it may be a mineral spirit that is a mixture of long-chain alkanes.
[0024]
In the case of the third solvent, it may be necessary to use a solvent different from that used in the first step (a solvent having a different purity even if it is the same), but the present invention is suitable for such a case. is there.
What is necessary is just to set the usage-amount of the said solvent suitably according to the use of a metal ultrafine particle independent dispersion liquid.
The ultrafine metal particle concentration can be adjusted at any time by heating in a vacuum after manufacturing the dispersion.
In the present invention, when producing a dispersion using metal ultrafine particles obtained by a chemical reduction method such as a liquid phase reduction method, as a raw material for producing metal ultrafine particles, for example, bishexafluoroacetyl A reducing raw material that is a metal-containing organic compound such as acetonate copper, nickel bisacetylacetonate, cobalt bisacetylacetonate, or the like can also be used.
[0025]
The reduction method is performed as follows, for example. In a state where the dispersant is added to the raw material, the raw material is thermally decomposed at a predetermined temperature to generate ultrafine metal particles. Almost all of the generated ultrafine metal particles are recovered in an independently dispersed state. The particle diameter of the ultrafine metal particles is about 100 nm or less. When the metal ultrafine particles are replaced with the third solvent, which is a solvent for producing dispersed metal ultrafine particles as described above, a desired metal ultrafine particle independent dispersion can be obtained. The obtained dispersion maintains a stable dispersion state even if it is concentrated by heating in vacuum.
[0026]
In order to improve the adhesion of the metal film that is the seed pattern for plating, a metal-containing organic compound (metal-containing organic compound) such as an organosilicon compound or an organomanganese compound is added to the above ultrafine metal particle independent dispersion. May be. As the organosilicon compound, it can be used as long as it is soluble in a nonpolar hydrocarbon that is a liquid main solvent (third solvent) at room temperature, and has a decomposition temperature of about 150 to 250 ° C. , Diphenylsilane, tetraallylsilane, decamethyltetrasiloxane, and the like can be used. The amount of addition may be about 0.5 wt% to 10 wt% as the weight of silicon with respect to the weight of metal (for example, copper) ultrafine particles. If the amount is less than 0.5 wt%, the adhesion is not improved. The greater the amount added, the better the adhesion. However, if it exceeds about 10 wt%, the resistance of the film increases and the adhesion of the plating increases. Becomes worse. Moreover, as an organic manganese compound, manganese octoate, manganese naphthenate, manganese linoleate, etc. can be used, for example. As the addition amount, 0.5 to 10 wt% can be used as manganese weight with respect to the metal (copper) ultrafine particle weight. If it is less than 0.5 wt%, the adhesion is not improved, and if it exceeds 10 wt%, the resistance value of the film increases and the plating becomes poor.
[0027]
In addition to the above organosilicon compounds and organomanganese compounds, examples of metal-containing organic compounds effective for ensuring adhesion include silicon, manganese, chromium, nickel, titanium, magnesium, aluminum, germanium, tantalum, niobium and vanadium. There is a fatty acid salt which is an organic compound containing at least one metal selected from. Of these metal fatty acid salts, those having a low decomposition temperature (about 300 ° C. or less) are effective. For example, magnesium, as a compound containing aluminum, can be mentioned _{(C 17 H 35 COO) 2} Mg, the _{(C 17 H 35 COO) 3} Al.
[0028]
According to the present invention, in addition to the method using an independent dispersion of ultrafine metal particles to which a metal-containing organic compound is added, a dispersion of only the metal-containing organic compound is used and directly on an insulating substrate by an inkjet method. After the base conductive film pattern is formed and fired, the base insulating conductive film pattern may be directly formed by an inkjet method using a nano ink made of the above-mentioned metal ultrafine particle independent dispersion, to which a metal-containing organic compound may be added. A method of forming a seed line on the surface, then forming a seed pattern by heating to evaporate the dispersant and the solvent in the ink, and forming a conductive film pattern thereon by electroless plating is also possible. This is useful for ensuring the adhesion between the substrate and the conductive film pattern. For example, a manganese octoate solution (solvent: tetradecane) is first applied onto a substrate to be treated by ink jet coating, and this is baked in the atmosphere, for example, at 230 ° C. for 10 minutes. Get a membrane. On this film, an ultrafine metal fine particle independent dispersion is applied by ink jet under the same conditions as described above, and this is heated to evaporate the dispersant and solvent, and then subjected to electroless plating. The obtained conductive film pattern has a specific resistance value of about 2 μmΩ · cm, and has good adhesion and film quality.
[0029]
【Example】
Examples of the present invention and comparative examples will be described below.
(Example 1)
Using a glass substrate, a Cu seed pattern was formed as follows.
Α-Terpineol was mixed with tetradecane solvent-dispersed Cu nanoink to adjust the viscosity to 5 cps and the concentration to 5 wt%. Using an inkjet apparatus, this nano ink was ejected onto a glass substrate heated to 100 ° C. to form a seed line, and the solvent and the dispersant were removed at 250 ° C. to form a linear Cu seed pattern having a width of 50 μm. . Then, the glass substrate on which the seed pattern was formed was immersed in a Cu electroless plating bath (composition: a known plating bath containing copper sulfate as a main component) for 30 minutes. As a result, a Cu thin film having a film thickness of about 5 μm was formed on the Cu seed pattern, and a conductive film pattern could be obtained. The resistivity of the film was 2.7 μmΩ · cm, and when a tape test for adhesion was performed, no peeling of the Cu film was observed from the substrate.
[0030]
When the substrate heating temperature was 60 ° C., the Cu fine particle concentration was 10 wt%, the viscosity was 20 cps, and the roughened state of the substrate surface was Rmax = 70 nm, the above operation was repeated. Results were obtained.
[0031]
(Comparative Example 1)
The method described in Example 1 was repeated. However, without heating the substrate, Cu nano ink was ejected onto the substrate at room temperature to form a seed line, and the solvent and the dispersant were removed at 250 ° C. The line width of the formed linear Cu seed pattern was 700 μm, and the seed pattern could not be refined.
[0032]
(Comparative Example 2)
The method described in Example 1 was repeated. However, a seed pattern was formed using 20 wt% Cu nano ink instead of 5 wt% Cu nano ink, and electroless plating was performed in the same manner as in Example 1. In this case, although the deposition speed of Cu at the initial stage of plating was increased, as a result of a tape test performed on the obtained conductive film pattern, peeling occurred between the substrate and the Cu film.
Moreover, when the roughened state of the substrate surface was set to Rmax = 5 nm and the operation of Example 1 was repeated, peeling occurred between the substrate and the Cu film.
[0033]
【The invention's effect】
According to the seed pattern forming method of the present invention, a high-purity seed pattern for plating can be formed by a simple method without using polysilane and thus without requiring a cleaning / waste liquid treatment step. If nano ink with a specific viscosity / concentration range is used, it is possible to ensure excellent adhesion between the conductivity and the substrate. If a substrate whose surface is roughened to a predetermined extent is used as the substrate to be processed, the substrate and the plating film can be effectively adhered to each other, and the pattern can be refined. Further, since the drawing is performed while maintaining the substrate temperature at 60 to 100 ° C., a satisfactory line width can be achieved even when the drawing line width cannot be controlled by the degree of surface roughness.
In addition, according to the conductive film pattern forming method of the present invention, since the conductive film pattern is formed on the plating seed pattern by electroless plating, a photolithography process is unnecessary, and the number of processes can be reduced. A conductive film pattern having a desired line width and good conductivity can be provided, and high adhesion of the conductive film pattern to the substrate to be processed can be achieved.

Claims (3)

Cu, Ag, ultrafine particles of a metal selected from Au and Pd, see contains a dispersant and an organic solvent, using a nano ink viscosity is 3～20Cps, by an ink jet method, directly, the surface roughness Rmax = 20 Plating characterized in that a seed line is drawn on a substrate having a thickness of ˜500 nm while maintaining the substrate temperature at 60 to 100 ° C., and the dispersant and solvent are evaporated by heating to form a plating seed pattern. Seed pattern forming method. Plating seed pattern forming method according to claim 1 Symbol placement, wherein the nano-ink is one that contains a 0.1 to 15% of the metal ultrafine particles. 3. A method for forming a conductive film pattern, comprising: forming a seed pattern for plating by the method according to claim 1; and forming a conductive film pattern on the seed pattern by electroless plating.