JP2003124591A - Electronic circuit board and its manufacturing method as well as copper-plating liquid for suppressing migration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electronic circuit board capable of accurately forming fine circuit wirings rigidly on the board and preventing migration between the circuit wirings and to provide a method for manufacturing the same and a copper-plating liquid for suppressing the migration. SOLUTION: The electronic circuit board 10A comprises a circuit wiring 8A of a laminated structure having a barrier metal thin film layer 2 formed by sputtering to become a barrier to the migration, a seed metal thin film layer 3 formed by sputtering for expediting the generation of plating of a conductive layer 5 on the layer 2, and the conductive layer 5 having a relatively large thickness and formed by plating on the layer 3, on the surface of a substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit board capable of preventing migration between circuit wirings, a method of manufacturing the same, and an etching solution for a spray method.

[0002]

2. Description of the Related Art A conventional method for manufacturing an electronic circuit board is to use a wiring of a predetermined wiring circuit, electrodes, and / or connection terminals (hereinafter collectively referred to as "circuit wiring") on a substrate (hereinafter referred to as "circuit wiring").
When forming on a "substrate"), a copper foil is attached to the entire surface of the substrate, a copper layer is formed by plating, etc., and a photoresist is applied to the entire surface, and the surface of the photoresist is then applied. After exposing the circuit wiring pattern on the substrate, it was generally developed to remove unnecessary portions of the metal where the photoresist was not present by etching to form a predetermined circuit wiring.

In this prior art method of manufacturing an electronic circuit board, the thickness of the metal layer formed on the board is usually 10 to 10.
It is 20 μm, and an unnecessary metal layer portion is removed from the surface side by etching.
The shape of the circuit wiring is a tapered cross-sectional shape, the variation of its accuracy is large at about ± 40 μm, the width of the circuit wiring is 75 μm, and the interval between adjacent circuit wiring is 75 μm (hereinafter,
L / S (Line & Space) = 75 μm / 75 μ
It was difficult to form a fine circuit wiring because there was a limit to the extent of "marked as m".

[0004]

In order to solve this problem, various techniques relating to miniaturization of circuit wiring are currently being developed. In the thin film technology currently under development, L on the substrate
/ S: It became possible to form circuit wiring of about 10 μm / 10 μm.

However, since the distance between circuit wirings has become narrower, migration between circuit wirings, which has not been a problem in the past, has come to occur.

The present invention is intended to solve such a problem and is capable of firmly adhering on a substrate and forming fine circuit wiring with high accuracy, and causing migration between the circuit wirings. It is an object of the present invention to provide an electronic circuit board having excellent migration resistance, a method of manufacturing the same, and a copper plating solution for suppressing migration generation.

[0007]

Therefore, in the electronic circuit board of the present invention, a barrier metal thin film layer formed by sputtering, which serves as a barrier against migration, is formed on the surface of the substrate, and a conductive film is formed on the barrier metal thin film layer. Circuit wiring having a laminated structure composed of a seed metal thin film layer formed by sputtering for promoting generation of plating of the layer and a relatively thick conductive layer formed by plating on the seed metal thin film layer To solve the above problems. It is preferable that both side surfaces of the circuit wiring are covered with a barrier metal thin film. The barrier metal thin film layer is preferably titanium, and the seed metal thin film layer and the conductive layer are preferably copper.

In the method of manufacturing an electronic circuit board of the present invention, in the method of manufacturing an electronic circuit board in which circuit wiring having a laminated structure composed of conductive layers formed by plating is formed on the substrate, migration onto the surface of the board is performed. A step of forming a barrier metal thin film layer serving as a barrier against the barrier metal by sputtering, a step of forming a seed metal thin film layer on the barrier metal thin film layer for promoting the generation of plating of the conductive layer by sputtering, and the seed metal thin film A step of forming a predetermined circuit wiring pattern using a plating resist on a layer, a step of plating a conductive material on the circuit wiring pattern, a step of removing the plating resist, and an exposure by removing the plating resist The barrier metal thin film layer and the seed metal thin film layer in the exposed portion are etched by a spray method. It adopts a method of forming a circuit wiring of the stacked structure through a manufacturing process including a step solves the above problems.

Further, in another method of manufacturing an electronic circuit board of the present invention, subsequent to the etching step, a step of coating the upper surface of the circuit wiring with a plating resist, and the circuit wiring having the upper surface coated with the plating resist. And a step of forming a barrier metal thin film layer that becomes a barrier against migration by electrolytic plating on both side surfaces of the electrolytic plating,
The problem is solved by adopting a method of forming a barrier metal thin film on both side surfaces of the circuit wiring through a manufacturing process including a step of removing the plating resist from the upper surface of the circuit wiring.

In these cases, it is desirable that the barrier metal thin film layer is titanium, and the seed metal thin film layer and the conductive layer are copper. Further, after the seed metal thin film layer is etched, the barrier metal thin film layer is removed. Etching is desirable.

Furthermore, the copper plating solution for suppressing the occurrence of migration of the present invention contains a substance that suppresses plating and a substance that imparts smoothness as additives. The amount of the additive mixture is 5 to 2 per 1 liter of the drug solution.
It is preferably 0 ml.

As described above, according to the electronic circuit board of the present invention, the barrier metal thin film layer of the circuit wiring prevents the occurrence of migration between the circuit wirings, and at the same time, the barrier metal thin film layer adheres firmly to the surface of the substrate. Is attached to
The conductive metal film is formed so as not to be easily peeled off, and because of the existence of the seed metal thin film layer formed in close contact with the surface thereof, the seed metal thin film layer is familiar with the conductive layer. By forming the barrier metal thin film layer of titanium which is easy to oxidize, it is difficult to ionize, and the barrier can be reliably formed,
In addition, by forming the seed metal thin film layer and the conductive layer with copper, a highly precise and fine circuit wiring can be formed by closely adhering to the substrate.

According to the method of manufacturing an electronic circuit board of the present invention, the fine and precise circuit wiring as described above can be easily formed on the organic substrate.

Further, according to the copper plating solution for suppressing the occurrence of migration of the present invention, abnormal growth of plating can be suppressed, and when copper plating is performed in the plating resist layer, copper plating at the corners of the bottom of the plating resist layer is suppressed. It is possible to suppress the growth of the copper alloy, obtain a uniformly grown pattern, easily form the circuit wiring with the present copper plating solution, and suppress the occurrence of migration between the circuit wirings.

[0015]

DETAILED DESCRIPTION OF THE INVENTION An electronic circuit board according to an embodiment of the present invention and a method for manufacturing the same will be described below with reference to FIGS.

FIG. 1 is a partially enlarged sectional view of an electronic circuit board according to a first embodiment of the present invention, FIG. 2 is a partially enlarged sectional view of an electronic circuit board according to a second embodiment of the present invention, and FIG. Process steps for explaining the method for manufacturing the electronic circuit board of the present invention shown in FIG.
FIG. 4 is a process diagram for explaining the method for manufacturing the electronic circuit board of the present invention shown in FIG. 2, and FIG. 5 is a semi-finished product state for explaining the growth state of copper plating by the copper plating solution of the present invention. FIG. 6 is a cross-sectional view of the partial electronic circuit board, and FIG. 6 is a graph showing the result of the migration test.

First, referring to FIG. 1, the first aspect of the present invention will be described.
The structure of the electronic circuit board of the embodiment will be described.

In FIG. 1, reference numeral 10A indicates, as a whole,
Refers to the electronic circuit board of the present invention. This electronic circuit board 10A
The circuit wiring 8A having a three-layer structure of the barrier metal thin film layer 2, the seed metal thin film layer 3, and the conductive layer 5 is formed on the substrate 1. The barrier metal thin film layer 2 is directly formed on the surface of the substrate 1 by sputtering, the seed metal thin film layer 3 is formed on the surface of the barrier metal thin film layer 2 by sputtering, and the seed metal thin film layer 3 is formed.
Has a structure in which the conductive layer 5 is formed by plating on the surface of, and has, for example, a pattern of L / S: 10 μm / 10 μm.

FIG. 2 shows an electronic circuit board 10B according to the second embodiment of the present invention. This electronic circuit board 10B
Of the electronic circuit board 10A has further improved anti-migration property than the electronic circuit board 10A. The circuit wiring 8B is formed by the barrier metal thin film layer 2 between the substrate 1 and the seed metal thin film layer 3. In addition, both side surfaces of the circuit wiring 8B are formed so as to be covered with the barrier metal thin film layers 7A and 7B2, and the structure has a more excellent migration resistance property than the electronic circuit board 10A. .

Next, a method of manufacturing the electronic circuit board on which the circuit wiring 8A shown in FIG. 1 is formed will be described with reference to FIG.

First, as shown in FIG. 3A, a substrate 1 is prepared, a barrier metal thin film layer 2 for preventing the occurrence of migration is formed on the surface thereof by sputtering, and a conductive layer 5 is formed by plating on it. A seed metal thin film layer 3 for promoting is formed by sputtering. For the barrier metal thin film layer 2, it is desirable to use a metal that easily becomes an oxide, and for the seed metal thin film layer 3, a metal having a high plating property is used.

Next, as shown in FIG. 3B, a plating resist layer 4 is formed on the surface of the seed metal thin film layer 3, and a desired circuit wiring pattern 4A is formed on the plating resist layer 4.

Next, as shown in FIG. 3C, a metal conductor is plated in the pattern 4A of the plating resist layer 4 to form a conductive layer 5. The plating at this time may be either electrolytic plating or electroless plating, and is not limited to either one.

Next, as shown in FIG. 3D, the plating resist layer 4 is removed after the plating is completed.

Then, as shown in FIG. 3E, the barrier metal thin film layer 2 and the seed metal thin film layer 3 exposed by removing the plating resist layer 4 are removed by etching. When etching the barrier metal thin film layer 2 and the seed metal thin film layer 3, the seed metal thin film layer 3 is first etched, and then the barrier metal thin film layer 2 is etched.
By selectively etching each layer, such as by etching, it is possible to form the circuit wiring 8A with high accuracy while suppressing side etching.

In this way, the circuit wiring 8A having a three-layer structure in which the barrier metal thin film layer 2, the seed metal thin film layer 3 and the conductive layer 5 are formed thereon as shown in FIG. The electronic circuit board 10A formed in the above is obtained.

Circuit wiring 8 of the electronic component device 10A of the present invention
A is difficult to ionize because the barrier metal thin film layer 2 serving as a seed metal is formed of a metal that is easily oxidized when exposed to air, and the oxide serves as a barrier, improving migration resistance between the adjacent circuit wirings 8A. Can be made.

Since the conductive metal layer 5 having a high plating property is used as a seed metal and the conductive layer 5 is formed by plating using the plating resist as a mask, the conductive layer 5 is adapted to the surface of the seed metal thin film layer 3. It is formed into a film.

Therefore, according to the method for manufacturing an electronic circuit board of the present invention, the circuit wiring 8A is firmly adhered to the board 1 as a whole, and the circuit wiring 8A is fine, highly accurate, and has migration resistance. It can be formed with an excellent structure.

Since it is possible to form the circuit wiring 8A which is fine and highly accurate and has excellent migration resistance, L
The circuit wiring 8A with a narrow / S can be formed, impedance matching can be easily taken, and a circuit corresponding to the high frequency characteristics in the GHz band can be formed.

Further, since the circuit wiring 8A can be thinned, it is possible to directly form an inductor or the like, which is conventionally mounted as a component, on the surface of the organic substrate 1, and further, it is possible to mount many components. This makes it possible to reduce the size of the electronic circuit board 10A at the same time.

Next, a method of manufacturing the electronic circuit board 10B on which the circuit wiring 8B shown in FIG. 2 is formed will be described with reference to FIG.

The circuit wiring 8A shown in FIG. 4A is the same as the circuit wiring 8 shown in cross section in FIG. 3E. The upper surface of the conductive layer 5 of all the circuit wiring 8A is shown in FIG.
As shown in B, it is covered with the plating resist layer 6.

Next, as shown in FIG. 4C, the circuit wiring 8
A barrier metal thin film layer 2A for preventing migration from occurring on both side surfaces 7A and 7B of the barrier metal thin film layer 2, the seed metal thin film layer 3 and the conductive layer 5 of A,
For example, the film is formed by electrolytic plating. Barrier metal thin film layer 2
It is desirable to use a metal that easily becomes an oxide for A.

Next, as shown in FIG. 4D, the plating resist layer 6 is removed after the plating of the barrier metal thin film layer 2A is completed.

In this way, the barrier metal thin film layer 2A as shown in FIG. 2 is continuous with the barrier metal thin film layer 2 between the surface of the substrate 1 and the seed metal thin film layer 3, and the seed metal thin film layer is formed. 3 and conductive layer 5 formed thereon
An electronic circuit board 10B is obtained in which circuit wirings 8B having a three-layer structure formed on both side surfaces 7A and 7B of the above are formed on the board 1.

Circuit wiring 8B of this electronic component device 10B
Since both sides 7A and 7B are covered with the barrier metal thin film layer 2A as compared with the circuit wiring 8A of the electronic circuit board 10A, the occurrence of migration between the adjacent circuit wirings 8B can be further prevented. it can. Other excellent features are the same as those of the electronic circuit board 10A of the first embodiment.

As an example, benzocyclobutane (BCB) was used as the insulating material of the thin film layer. The barrier metal thin film layers 2 and 2A are made of titanium (Ti), the seed metal thin film layer 3 is made of copper (Cu), the plating resist layer 4 is made of Tokyo Ohka PMER series, and the conductive layer 5 is made of copper. (Cu) was used.

The barrier metal thin film layers 2 and 2A have a Ti thickness of 250 Å, and the seed metal thin film layer 3 has a Cu thickness of 50.
It was set to 00Å. Further, the thickness of the plated Cu of the conductive layer 5 is 1
It was set to 0 μm.

Ti easily oxidizes when it comes into contact with air, and its oxide TiO serves as a barrier to improve the migration resistance property between the adjacent circuit wirings 8A. Particularly, in the case of the circuit wiring 8B, since both side surfaces 7A and 7B (FIG. 2) are covered with an oxide film, the migration resistance can be further improved as compared with the circuit wiring 8A.

Further, the electronic circuit board 10A of the first embodiment
In the manufacturing method of 1., even if the Ti residue remains when the barrier metal thin film layer 2 of Ti is etched back, it is more likely to be stable as an oxide TiO, and compared with the case where another metal such as Ni is used. The occurrence of migration can be further suppressed.

The etching solution used to form the circuit wiring 8A of the first embodiment is the seed metal thin film layer 3
The etching of Cu is performed by using a mixed acid solution SO-YO containing nitric acid and sulfuric acid as main components, manufactured by Kanto Chemical Co.
Etching of i Kanto Chemical mixed acid solution containing hydrofluoric acid SO
-1 was used.

Next, the copper plating of the conductive layer 5 will be described.

Usually, the plating grows omnidirectionally and tends to enlarge the grains. In the present invention, copper sulfate was used for the plating solution, but by adding a component (polymer or the like) that suppresses the growth of plating, as shown by the arrow in FIG. By suppressing the plating growth, the plating could be uniformly grown in the pattern 4A.

Further, a component which gives gloss and has smoothness, for example, PEG (polyethylene glycol) or JG
By adding B (Janus Green B) or the like, it was possible to promote miniaturization and flattening of the particles.

As a result, the activation energy of copper in the conductive layer 5 can be suppressed to a low level, and with the conventional plating solution,
The variation in the range of 3 μm per 1 mm of the circuit wiring was suppressed to the variation of 1 μm or less per 1 mm of the circuit wiring by using the migration-inhibiting copper plating solution of the present invention.

At the time of study, the plating liquid manufactured by Nippon Electroplating Engineering Co., Ltd. (EE
The effect was observed by using MF-Cu300 of JA) and adding a dedicated Starter as an additive in an amount of 5 to 20 ml / L.

In addition, it was also confirmed that the migration resistance was improved by completing the growth of copper particles by annealing at about 210 ° C. after copper plating.

The accuracy of the circuit wiring 8 of the electronic circuit board manufactured by the conventional technology and the manufacturing method of the present invention is as follows:
Contrary to m ± 40 μm (the cross-sectional shape is trapezoidal), according to the method for manufacturing an electronic circuit board of the present invention, the width is 10 μm.
It could be formed with m ± 2 μm (rectangular cross section). Thus, the circuit wiring could be formed finely and highly accurately, and the migration resistance could be improved.

FIG. 6 shows the test results of the migration resistance characteristics of the conventional circuit wiring and the circuit wirings 8A and 8B of the present invention. In FIG. 6, the horizontal axis represents the test time (hr) and the vertical axis represents the cumulative failure rate (%). This Figure 6
As is clear from the above, in the conventional circuit wiring, migration occurs at a high level of 20% to 80% in about 10 hours, but in the circuit wirings 8A and 6B of the present invention,
L / S: Between circuit wirings of 10 μm / 10 μm, it can be seen that the occurrence of migration remains within a range of 10% to 50% even after 550 hours or more under a test condition of 85 ° C., relative humidity of 85%, and 10V. .

In order to obtain higher-performance characteristics with less loss at high frequencies, it is desirable to use a substrate having high heat resistance as the material for the base substrate. For example, the LC
In addition to P (liquid crystal polymer), PI (polyimide), PPE
(Polyphenyl ether) and the like.
Examples of the insulating material of the thin film layer include BCB (benzocyclobutene), PI, and PNB (polynorporne).

[0052]

As described above, according to the present invention,
As a whole, it is excellent in migration resistance, and circuit wires can be tightly adhered and formed firmly on a substrate with precision fine wires. Therefore, 1. 1. High-precision circuit wiring can be obtained, impedance matching can be easily achieved, and a circuit corresponding to high frequency characteristics in the GHz band can be formed. 2. Inductors, which were conventionally mounted as components, can be directly formed on the surface of the board. Many excellent effects can be obtained, such as being able to mount many parts and simultaneously downsizing the electronic circuit board itself.

[Brief description of drawings]

FIG. 1 is a partially enlarged cross-sectional view of an electronic circuit board according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of an electronic circuit board according to a second embodiment of the present invention.

FIG. 3 is a process chart for explaining a method for manufacturing the electronic circuit board of the present invention shown in FIG.

FIG. 4 is a process drawing for explaining the manufacturing method of the electronic circuit board of the present invention shown in FIG.

FIG. 5 is a sectional view of a partial electronic circuit board in a semi-finished product state for explaining the growth state of copper plating by the copper plating solution of the present invention.

FIG. 6 is a graph showing the results of a migration test.

[Explanation of symbols]

1 ... Substrate, 2 ... Barrier metal thin film layer, 3 ... Seed metal thin film layer, 4, 6 ... Plating resist, 5 ... Conductive layer, 8A ...
Circuit wiring of the first embodiment, 8B ... Circuit wiring of the second embodiment, 10A ... Electronic circuit board of the first embodiment of the present invention, 1
0B ... Electronic circuit board according to second embodiment of the present invention

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4E351 BB32 BB33 BB36 CC03 CC06                       DD04 DD11 GG12 GG20                 4K023 AA19 BA06 CB32                 4K024 AA09 BA09 BB11 CA01 CA02                       DB01                 5E343 BB24 BB35 DD25 DD43 GG02                       GG08 GG14

Claims (10)

[Claims] 1. A barrier metal thin film layer formed on a surface of a substrate by sputtering to serve as a barrier against migration, and a seed formed on the barrier metal thin film layer by sputtering to promote generation of plating of a conductive layer. An electronic circuit board having a circuit wiring of a laminated structure formed of a metal thin film layer and a relatively thick conductive layer formed by plating on the seed metal thin film layer. 2. The electronic circuit board according to claim 1, wherein both side surfaces of the circuit wiring are covered with a barrier metal thin film. 3. The electronic circuit board according to claim 1, wherein the barrier metal thin film layer is titanium, and the seed metal thin film layer and the conductive layer are copper. 4. A method of manufacturing an electronic circuit board, comprising: forming a circuit wiring having a laminated structure in which a conductive layer formed by plating is formed on a substrate with a barrier metal thin film layer sandwiched therebetween; Forming a barrier metal thin film layer as a barrier against migration by sputtering, forming a seed metal thin film layer on the barrier metal thin film layer to promote plating formation of the conductive layer by sputtering, and forming the seed metal By forming a predetermined circuit wiring pattern on the thin film layer using a plating resist, plating a conductive material on the circuit wiring pattern, removing the plating resist, and removing the plating resist. Manufacturing process including a step of etching the exposed portion of the barrier metal thin film layer and the seed metal thin film layer A method for manufacturing an electronic circuit board, characterized in that the circuit wiring having the laminated structure is formed through the above steps. 5. A step of covering the upper surface of the circuit wiring with a plating resist subsequent to the etching step, and a barrier serving as a barrier against migration by electrolytic plating on both side surfaces of the circuit wiring having the upper surface coated with the plating resist. The circuit wiring having a laminated structure according to claim 2, wherein the circuit wiring is formed through a manufacturing process including a step of forming a metal thin film layer by electrolytic plating and a step of removing the plating resist from the upper surface of the circuit wiring. The method for manufacturing an electronic circuit board according to claim 4. 6. The method of manufacturing an electronic circuit board according to claim 4, wherein the conductive layer of the conductive material is annealed after the plating of the conductive material. 7. The method of manufacturing an electronic circuit board according to claim 4, wherein the barrier metal thin film layer is titanium, and the seed metal thin film layer and the conductive layer are copper. 8. The method of manufacturing an electronic circuit board according to claim 4, wherein the barrier metal thin film layer is etched after the seed metal thin film layer is etched. 9. A migration-inhibiting copper-plating solution comprising copper sulfate as a main component, and a plating-suppressing substance and a smoothing substance added as additives. 10. The copper plating solution for suppressing migration according to claim 9, wherein the amount of the mixed solution of the additive is 5 to 20 milliliters per liter of the chemical solution.