JPH08111414A - Forming method for laminated wiring, and circuit board - Google Patents

Abstract

PURPOSE: To prevent migration and corrosion surely in a laminated wiring layer with respect to a circuit board and a method for forming a laminated wiring. CONSTITUTION: A metallic thin film 21 for protecting a main conductor is formed on a side face and a bottom of an opening 73 in a regist layer 53 on a substrate 1. After a main conductor thin film 33 and a metallic thin film 42 for protecting the main conductor are formed on the thin film 22, the resist layer 53 is removed. The metallic thin film 21 for protecting the main conductor are formed only on the bottom of the opening 73 in the resist layer 53, and the main conductor thin film 33 is formed on the metallic thin film 22. The resist layer 53 is removed. In addition, a resist layer 54 is formed in a state that a sidewall part of a double-layer body 8 made up of laminated formation patterns of the main conductor thin film 33 and the lower metallic thin film 21 is exposed. After a metallic thin film 43 for protecting the main conductor is formed on the upper face and the sidewall part of the double-layer body 8, the resist layer 54 is removed. In a circuit board, the upper, lower and both side faces of thin-film main conductors 63a and 64a are covered with metallic films 63b, 63c, 64b, and 64c to form laminated wirings 63 and 64.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a laminated wiring which prevents migration and corrosion of a main conductor, and a circuit board on which the laminated wiring is formed.

[0002]

2. Description of the Related Art In a thin film multilayer circuit board in which insulating layers and wiring layers are alternately stacked, polyimide is generally used for the insulating layer, which has excellent heat resistance, stability, and strength, and the wiring is made of copper (Cu) or gold.
The main components are (Au), silver (Ag), and aluminum (Al).

In such a circuit board, wiring migration and corrosion are prevented, for example, when a wiring made of low-cost, low-cost copper is directly laminated on the polyimide layer,
In order to prevent migration of copper that gradually diffuses into the polyimide, in conventional wiring using copper as the main conductor, chromium with a thickness of about 800 Å is generally laminated on the top and bottom of copper with a thickness of about 5 μm, and Cr Cu 3 Layer wiring is used.

A general manufacturing method of such a three-layer wiring is as follows: patterning by etching from a three-layer film of Cr having a thickness of about 800Å, Cu having a thickness of about 5 μm, and Cr having a thickness of about 800Å. Cr of about 800Å and thickness of 50
A two-layer film of Cu of about 00Å is formed on the entire surface of the substrate, a plating resist is formed so that a predetermined portion of the two-layer film is exposed, Cu is plated on the Cu layer of the two-layer film, and the plating resist is removed. After that, the two-layer film is removed by etching to form a resist exposing the plated copper, a Cr thin film is formed thereon, and then the resist and Cr on the resist are removed.

FIG. 4 is an explanatory view of a conventional laminated wiring and a manufacturing method thereof, and FIGS. 4 (a) to 4 (d) are explanatory views of the above-mentioned method of forming a laminated wiring by etching a laminated metal film. (e) to (k) are explanatory views of the above-described method of forming a laminated wiring by using the lift-off method.

In FIG. 4A, a Cr film 2 having a thickness of about 800 Å, a Cu film 3 having a thickness of about 5 μm, and a Cr film 4 having a thickness of about 800 Å are sputtered or sputtered on the surface of the insulating substrate 1. Laminate by vapor deposition.

Next, as shown in FIG. 4 (b), a resist layer 5 corresponding to the wiring pattern to be formed is formed on the Cr film 4, and then the resist layer 5 is used as shown in FIG. 4 (c). Then, unnecessary portions of the Cr film 2, the Cu film 3, and the Cr film 4 are removed (etched).

Next, when the resist layer 5 is removed (eliminated), Cr Cu Cr is formed on the surface of the substrate 1 as shown in FIG. 4 (d).
3 layer wiring 6 is formed. In Fig. 4 (e), a Cr film 2 having a thickness of about 800 Å and a thickness of 5000 is formed on the surface of the insulating substrate 1.
After the Cu film 31 having a thickness of about Å is laminated by sputtering or vapor deposition, a plating resist layer 51 having an opening 71 corresponding to the wiring pattern to be formed is formed on the Cu film 31 as shown in FIG. 4 (f). To form.

Next, in order to secure the thickness of the main conductor, FIG. 4 (g)
As shown in, the exposed portion of the Cu film 31 has a thickness of about 5 μm.
After forming the plated layer 32, the resist layer 51 is removed (melted) as shown in FIG.

Next, the exposed Cu film 31 and the exposed Cr film 2 are removed (melted / etched) to remove Cr as shown in FIG. 4 (i).
A three-layer body 61 in which a Cu plating layer 32 is laminated on a thin film two-layer body formed by patterning the film 2 and the Cu film 31 is formed. In this process, the surface of the plating layer 32 is exposed as a Cu film.
Removed with 31.

Next, as shown in FIG. 4 (j), a resist layer 52 exposing the plating layer 32 is formed, a Cr film 41 having a thickness of about 800 Å is formed on the plating layer 32 and the resist layer 52, and then the resist is formed. When the layer 52 is removed (eliminated), the resist layer 52 is removed.
The unnecessary portion of the Cr film 41 adhered to the surface is removed together with the resist layer 52.
After being lifted off, a four-layer wiring 62 of Cr Cu Cu Cr is formed on the surface of the substrate 1 as shown in FIG. 4 (k).

[0012]

As described above,
Conventional laminated wiring in which the main conductor is sandwiched by its protective metal6.
In the wiring 62, copper is exposed on the side wall surface of a main conductor, for example, copper, and the end surface of the main conductor exposed on the side wall surface contacts the polyimide. Therefore, it is incomplete as a means for preventing migration and corrosion.

[0013] Incidentally, to cover the copper side wall surface of the laminated wiring 6,62, chromate on its side wall surface _{(Cr 2 O 3 · Cr O} 3 · x
H ₂ O) film can be formed. However, the chromate film has problems in reliability and chemical stability, and is not a sufficient solution.

[0014]

A first aspect of the present invention for reliably preventing migration and corrosion of laminated wiring.
In the manufacturing method, a resist layer having an opening corresponding to the wiring pattern is formed on the surface of the substrate, and a first main conductor protecting metal thin film is formed on at least a wall surface and a bottom surface of the opening, A main conductor thin film is formed on the first main conductor protecting metal thin film, a second main conductor protecting metal thin film is formed on the main conductor thin film, and the main conductor thin film on the resist layer and the Removing the second main conductor protecting metal thin film together with the resist layer.

The second manufacturing method of the present invention for surely preventing the migration and corrosion of the laminated wiring is the first manufacturing method which has the opening corresponding to the wiring pattern on the surface of the substrate.
Forming a resist layer, and forming a first main conductor-protecting metal thin film, which is adhered only to the bottom in at least the opening of the first resist layer, on the first main conductor-protecting metal thin film. Forming a main conductor thin film, and removing the first main conductor protecting metal thin film and the main conductor thin film, which are deposited on the first resist layer, together with the first resist layer, A two-layer body is formed in which a formation pattern of the main conductor thin film is laminated on a formation pattern of the main conductor protection metal thin film, and a second resist layer having an opening where the side wall surface of the two-layer body is exposed is formed. A second main conductor protecting metal thin film is formed on the surface of the substrate and is deposited on at least the upper surface and the sidewall surface of the two-layer structure, and the second thin film is deposited on the second resist layer. 2) removing the main conductor protecting metal thin film together with the second resist layer.

The circuit board of the present invention for surely preventing the migration and corrosion of the laminated wiring is such that the laminated wiring formed on the substrate has a lower surface and an upper surface of the main conductor having a rectangular cross-section formed by patterning a thin film, and both left and right side wall surfaces. Then, a protective metal film for the main conductor is deposited.

[0017]

As described above, the method for forming a laminated wiring and the circuit board according to the present invention provide a structure in which the main conductor of the laminated wiring is completely covered with a protective metal and a manufacturing method thereof. The body will not come into contact with the polyimide.

Therefore, the conventional migration and corrosion caused by the contact of the side wall surface of the main conductor with the polyimide are surely prevented by the present invention.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a method for forming a laminated wiring and a circuit board according to an embodiment of the present invention, and FIGS.
1A to 1J are explanatory views of a method of forming a laminated wiring and a circuit board in a second embodiment.

In FIG. 1 (a), a resist layer 53 having an opening 73 corresponding to a desired wiring pattern is formed on the surface of the insulating substrate 1 by a usual method, for example, to a thickness of about 15 μm (the thickness of the wiring to be formed). About 3 times the length).

Next, as shown in FIG. 1 (b), a thickness of at least 8 is applied to the bottom surface of the opening 73 and the side wall surfaces of the left and right openings.
A Cr thin film 21 of about 00Å is formed. Then, the Cr thin film 21
As shown in FIG. 1 (c), a Cu thin film 33 with a thickness of about 5 μm is formed on the upper surface of the Cu thin film 33.
When the resist layer 53 is removed (eliminated) after the thin film 42 is formed, the Cu thin film 33 and the Cr thin film 42 deposited on the resist layer 53 are removed (lifted off) together with the resist layer 53, as shown in FIG. As shown in FIG. 3, on the surface of the substrate 1, a protective layer 63b patterned from the Cr thin film 21 is adhered to the left and right side wall surfaces and the lower surface of the copper main conductor 63a patterned from the Cu thin film 33. The laminated wiring 63 on which the protective layer 63c patterned from the Cr thin film 42 is adhered is completed on the upper surface.

In the above embodiment, the Cr thin film 21 which needs to be deposited on the side wall surface of the opening 73 is formed by oblique sputtering, and the Cu thin film 33 and the Cr thin film 42 are formed by oblique sputtering, vertical sputtering or vapor deposition. To do.

In FIG. 1 (e), a resist layer 53 having an opening 73 corresponding to a desired wiring pattern is formed on the surface of the insulating substrate 1 by a conventional method, for example, with a thickness of about 15 μm (the thickness of the wiring to be formed is (Approx. 3 times the height), and then, as shown in FIG. 1 (f), so as not to adhere to the opening wall of the opening 73,
A Cr thin film 21 having a thickness of about 800 Å and a Cu thin film 33 having a thickness of about 5 μm are formed on the resist layer 53.

Next, when the resist layer 53 is removed (eliminated), a two-layer body 8 in which Cu is stacked on Cr is formed on the surface of the insulating substrate 1 as shown in FIG. 4 (g). Therefore, in FIG.
As shown in (h), after forming the resist layer 54 in which the left and right side wall surfaces of the two-layer body 8 are exposed, for example, the resist layer 54 having an opening for forming a gap of about 5 μm between the side wall surface of the two-layer body 8 is formed. As shown in FIG. 1 (i), a Cr thin film 43 deposited on at least the side wall surface of the two-layer body 8 is formed to have a thickness of, for example, about 800 Å.

Next, when the resist layer 54 is removed (eliminated), as shown in FIG. 4 (j), on the surface of the insulating substrate 1, Cr is formed on the lower surface of the copper main conductor 64a patterned from the Cu thin film 33.
A protective layer 64b patterned from the thin film 21 is deposited, and a laminated wiring 64 in which a protective layer 64c patterned from the Cr thin film 43 is deposited on the upper surface of the main conductor 64a and the left and right side wall surfaces is completed.

In the above embodiment, the Cr thin film 43 is formed by oblique sputtering, and the Cr thin film 21 and the Cu thin film are formed.
33 is formed by vertical sputtering or oblique sputtering or vapor deposition that does not adhere to the side wall surface of the opening.

FIG. 2 is an explanatory view of oblique sputtering, and FIG.
FIG. 4 is an enlarged cross-sectional view of a thin film formed by oblique sputtering. In FIG. 2, reference numeral 81 is a target, 82 and 83 are arrows indicating the direction in which metal particles are ejected from the target 81 toward the opening 73 of the resist layer 53, 1 is an insulating substrate in which the distance from the target 81 is L ₁ . 1 'is an insulating substrate in which the distance between the target 81 and L _2, theta ₁ is an angle of the arrow 82 (metal particle emission angle), the theta ₂ is the angle (metal particle emission angle) of the arrow 83.

Then, an oblique sputtering apparatus, for example, a substrate 1 located above the target has a revolution radius of 25 cm,
In an oblique sputtering apparatus in which the diameter of the disk-shaped target whose center coincides with the revolution axis of the substrate 1 is 20 cm, when the distance L ₁ between the target 81 and the insulating substrate 1 is 15 cm,
The metal particle emission angle θ ₁ is about 15 to 90 degrees, and the thin film 21 is formed on the side wall surface of the opening 73 as shown in FIG.

However, in the oblique sputtering apparatus, the distance L ₂ between the target 81 and the insulating substrate 1'is 40 cm.
Then, the metal particle emission angle θ ₂ becomes about 40 to 90 degrees, and the thin film 21 is hardly formed on the side wall surface of the opening 73 as shown in FIG. 3B.

Therefore, the oblique sputtering apparatus is
By changing the distance between the target 81 and the insulating substrate, it can be used not only as the original oblique sputtering of the apparatus but also as oblique sputtering which is almost close to vertical sputtering.

In the thin-film multi-layer circuit board, the main conductor of the wiring is mainly composed of copper (Cu), gold (Au), silver (Ag), and aluminum (Al). As a protective metal against corrosion,
Chromium (Cr), titanium (Ti), zirconium (Zr), hafnium (Hf), nickel (Ni), cobalt (Co), platinum (Pt),
Gold (Au) / palladium (Pd) -based materials are used.

In the above embodiment of the present invention, copper is used for the main conductor and chromium is used for the protective metal,
It is apparent from the embodiments of the present invention that the present invention is not limited to such embodiments and is applied to a laminated wiring using the gold or the like as a main conductor and the titanium or the like as a protective metal. .

[0033]

As described above, according to the present invention, the migration and corrosion of the main conductor of the wiring are surely prevented, and the reliability and life of the thin film circuit board are improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a method of forming a laminated wiring and a circuit board according to an embodiment of the present invention.

FIG. 2 is an explanatory view of oblique sputtering.

FIG. 3 is an enlarged cross-sectional view of a thin film formed by oblique sputtering.

FIG. 4 is an explanatory view of a conventional laminated wiring and its manufacturing method.

[Explanation of symbols]

 1 substrate 8 two-layer body 21 first main conductor protective metal thin film 33 main conductor thin film 42,43 second main conductor protective metal thin film 53,54 resist layer 63,64 laminated wiring 63a, 64a main conductor 63b, 63c , 64b, 64c Main conductor protection layer

Claims (8)

[Claims] 1. A resist layer having an opening corresponding to a wiring pattern is formed on a surface of a substrate, and a first main conductor protecting metal thin film is formed to adhere to at least a side wall surface and a bottom surface of the opening, A main conductor thin film is formed on the first main conductor protecting metal thin film, a second main conductor protecting metal thin film is formed on the main conductor thin film, and the main conductor thin film on the resist layer and Removing the second main conductor protecting metal thin film together with the resist layer. 2. The method for forming a laminated wiring according to claim 1, wherein the first main conductor protecting metal thin film is formed by first oblique sputtering, and the main conductor thin film and the second main conductor protecting metal thin film. To
A method for forming a laminated wiring, comprising: forming by a second oblique sputtering in which a distance between the target and the substrate is larger than that in the first oblique sputtering. 3. A first main conductor protection formed by forming a first resist layer having an opening corresponding to a wiring pattern on a surface of a substrate, and depositing only a bottom portion at least in the opening of the first resist layer. A metal thin film for protection, a main conductive thin film is formed on the first metal thin film for protecting the main conductor, and the first metal thin film for protecting main conductor is deposited on the first resist layer; The main conductor thin film is removed together with the first resist layer to form a two-layer body in which the formation pattern of the first main conductor protection metal thin film is laminated with the formation pattern of the main conductor thin film, A second main conductor protection metal which is formed on the surface of the substrate with a second resist layer having an opening exposing the side wall surface of the two-layer body, and is adhered to at least the upper surface and side wall surface of the two-layer body. Forming a thin film and protecting the second main conductor deposited on the second resist layer And removing the metal thin film for use with the second resist layer. 4. The laminated wiring forming method according to claim 3, wherein the first main conductor protecting metal thin film is formed by the second oblique sputtering according to claim 2. Wiring formation method. 5. The method of forming a laminated wiring according to claim 1, wherein chromium is used for the first main conductor protecting metal thin film and the second main conductor protecting metal thin film, and the main conductor thin film is used. A method of forming a laminated wiring, characterized in that copper is used for. 6. A laminated wiring formed on a substrate, wherein a protective metal film for the main conductor is deposited on the lower and upper surfaces of a rectangular-shaped main conductor patterned in a thin film, and both left and right wall surfaces of the main conductor. A circuit board characterized by: 7. The circuit board according to claim 6, wherein the protective metal film of the main conductor is adhered to a lower surface of the main conductor and both left and right wall surfaces of the main conductor, and the main conductor of the main conductor. A circuit board comprising a second metal film deposited on the upper surface. 8. The circuit board according to claim 6, wherein the protective metal film of the main conductor has a first metal film attached to a lower surface of the main conductor, and upper and left side wall surfaces of the main conductor. A circuit board comprising a second metal film adhered to and.