JPH05299846A - Wiring board manufacturing method - Google Patents

Abstract

(57) [Abstract] [Purpose] By forming the metal wiring by electroless plating, it is possible to perform an easy operation with an inexpensive and small device.
Accurately form the dimensions of metal wiring. [Structure] An insulating layer of photosensitive polyimide is laminated on a Si substrate body. Next, the surface of the insulating layer is roughened in plasma. A second insulating layer is applied on the surface, and the wiring pattern is exposed to UV to be developed and etched. next,
Electroless copper plating is performed to form a metal layer. By the subsequent cleaning, the metal attached to the surface of the second insulating layer is removed, and the surface is ashed to roughen it. An insulating film of photosensitive polyimide is applied and UV exposure is performed to form a via hole pattern. A via hole is formed by development and etching, and electroless copper plating is performed to form a metal layer in the via hole. Then, ashing is performed to roughen the surface of the insulating layer and the surface of the metal layer. An insulating layer of photosensitive polyimide is laminated on this surface. Thereafter, this process is repeated to form a multilayer thin film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board, and more particularly to a method for manufacturing a multilayer wiring board for electronic components mounted on electronic equipment such as personal computers and word processors.

[0002]

2. Description of the Related Art Conventionally, in order to manufacture a multilayer wiring board, an insulating layer is laminated on a ceramic or Si substrate, a metal thin film is formed on the surface by a vapor deposition / sputtering method, and a resist is further formed thereon. After coating, exposing and developing using a mask to remove unnecessary portions by etching, the resist is peeled off to form a first-layer metal wiring. Then, the process of laminating an insulating layer on the surface to form a via hole, forming a metal thin film again, and forming a second-layer metal wiring by etching is repeated.

5, FIG. 6, FIG. 7, and FIG. 8 are schematic cross-sectional views of a wiring board at the stage of forming a multilayer wiring on an insulating layer by a conventional method. As shown in FIG. 5 (a), a polyimide 21 serving as an insulating layer is laminated on the Si substrate body 11 and cured. A metal layer 41 to be wiring is formed thereon by a vapor deposition method or a sputtering method, and a negative resist layer 51 is laminated on the surface thereof. Next, as shown in Fig. 5 (b), the mask
Using 61, the wiring pattern of the first layer is exposed and developed from above, and the resist layer 4 and the metal layer 41 are etched as shown in FIG. 5C. After the resist layer 51 is peeled off, the polyimide 21 is laminated as shown in FIG. 5 (d) to form the first-layer metal wiring.

As shown in FIG. 6 (e), a metal layer 41 is formed on the surface of the polyimide 21 by vapor deposition or sputtering, and a positive resist layer 51 is laminated. Next, as shown in FIG. 6 (f), a mask 62 is used to expose from above and develop,
The resist layer 51 and the metal layer 41 are etched as shown in (g), and the resist layer 51 is peeled off as shown in FIG. 6 (h). After that, as shown in FIG. 7 (i), the polyimide 21 is etched using the metal layer 41 as a mask to form via holes 72, 72 ... And the metal layer 41 used as the mask is peeled off as shown in FIG. 7 (j). , And the via layer 72 is filled with the metal layer 41 in a plating process.

Next, as shown in FIG. 7 (k), a metal layer 41 is formed by an evaporation method or a sputtering method, and a negative resist layer 51 is laminated on the surface thereof, and as shown in FIG. 8 (l). Mask 63
Exposing the second layer wiring pattern from above using
develop. Then, as shown in FIG. 8 (m), the resist layer 51
Then, the metal layer 41 is etched to form a second-layer metal wiring. Then, the resist layer 51 is peeled off as shown in FIG. 8 (n), and the polyimide 21 is laminated thereon as shown in FIG. 8 (o) to manufacture a multilayer wiring board.

[0006]

As described above, the vapor deposition method and the sputtering method are mainly used for forming the metal wiring in the multilayer wiring board, and the apparatus used for these is large and expensive, and the inside of the chamber is In many cases, the operation method is complicated, such as a vacuum state.

Further, when the metal wiring is formed by etching the metal thin film as described above, the finished width dimension of the metal wiring tends to be smaller than a desired dimension, and the width is less than ten and several microns. When forming the metal wiring, there is a problem that there is a possibility of disconnection.

The present invention has been made in view of the above circumstances, and by forming the metal wiring by electroless plating, it is possible to perform a simple operation with a small and inexpensive device.
It is an object of the present invention to provide a method for manufacturing a wiring board, in which the dimensions of metal wiring are accurately formed.

[0009]

A method of manufacturing a wiring board according to the present invention comprises a step of laminating a first photosensitive resin on a substrate and subjecting the surface of the first photosensitive resin to plasma treatment. Laminating a second photosensitive resin on the first photosensitive resin,
A step of forming an opening based on the wiring pattern in the second photosensitive resin by exposing the plasma-treated surface of the first photosensitive resin; and a metal wiring in the opening by electroless plating. And a forming step.

[0010]

In the method of manufacturing a wiring board of the present invention, the metal wiring is formed by electroless plating. Compared with the conventional method of forming a metal thin film by etching, in the electroless plating, the metal wiring is formed with high dimensional accuracy by an inexpensive and small device and a simple operation method.

Further, when the metal wiring is formed by electroless plating, it is considered that there is a problem in its adhesiveness. Ni, C on the surface of the photosensitive thin film by normal electroless plating
When depositing a metal such as u or Ag, it is difficult for the substance that serves as the nucleus of this deposit, such as Na ⁺ , to adhere to the surface of the untreated photosensitive resin, and the formed metal thin film does not undergo electroless plating. The less adhesive it is washed away during the washing process. However, in the present invention, since the surface of the photosensitive resin on which the metal wiring is formed is roughened by the plasma treatment, the substance that becomes the nucleus of the precipitate is likely to adhere, and the adhesive force is increased.
Similarly, the adhesive force between the photosensitive resins also increases.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments thereof. FIG. 1 is a flow chart showing a procedure for forming a multilayer wiring on a photosensitive resin according to the present invention, and FIGS. 2, 3 and 4 are schematic sectional views at that stage. Note that (a), (b) shown in FIGS. 2, 3, and 4 ...
The schematic cross-sectional view of FIG. 1 corresponds to the steps of FIGS.

As shown in FIG. 2 (a), an insulating layer of photosensitive polyimide is formed on a Si substrate main body 11 having a size of 40 × 40 × 0.4 mm.
31 is laminated. This photosensitive polyimide uses a negative type Photo Nice "UR-3840" (manufactured by Toray Industries, Inc.), and a 1.5 cm ³ photo Nice "UR-3840" is spin coated (500r.pm × 30min. .pm × 30 min. (the same conditions below) to apply a thickness of 5 μm. And pre-cure process (N ₂ atmosphere, 80 ° C x 2hour, same condition below), UV exposure (g line: wavelength 405nm x 30sec., Same condition below), cure process (140 ° C x 30min.
n., and the same conditions below) are performed to cure the insulating layer 31.

Next, ashing (600mtorr, 2.1 l / mi
n. O ₂ atmosphere, RF 400 W, 30 min., the same conditions are applied), and the surface of the insulating layer 31 is roughened in CO ₂ plasma as shown in FIG. 2 (b). Insulating layer in the ashing process
31 Asperities are formed at a depth of 0.2 to 0.7 μm from the surface. This is because if it is shallower than this, it is difficult to attach the metal wiring, and if it is deeper than this, the attached metal wiring may be broken or short-circuited. Then, as shown in FIG. 2 (c),
A second insulating layer 32 of the same photosensitive polyimide, Photo Nice "UR-3840" (manufactured by Toray Industries, Inc.) is applied to the surface of the roughened insulating layer 21 by spin coating to a thickness of 5 .mu.m and pre-cured.

The insulating layer 32 formed in this manner has a structure shown in FIG.
As shown in FIG. 3, the wiring pattern is UV exposed from above using a mask 64, and development and etching (25 ° C. × 3 min.) Are performed as shown in FIG. 3 (e). Further cure,
The insulating layer 32 is cured. The opening formed in this way
The surface roughened by the ashing process shown in FIG. 2B is exposed at the bottom surface of 71, 71 ....

Next, an electroless copper plating process is performed, and the process shown in FIG.
As shown in (f), metal layers 42, 42 ... Are formed in the openings 71, 71. The electroless copper plating treatment is performed under the conditions shown in Table 1. By the subsequent cleaning, the second insulating layers 32, 32 ...
The metal adhering to the surfaces of the insulating layers 32, 32 ... And the surfaces of the metal layers 42, 42 ... Are ashed and roughened to form the first-layer wiring.

[0017]

[Table 1]

As shown in FIG. 3 (g), further on this surface,
An insulating film 33 of photosensitive polyimide is applied. This photosensitive polyimide is a positive type Photo Nice "DV-505"
(Manufactured by Toray Industries, Inc.) is used. Then, UV exposure is carried out from above using the mask 65 to form a via hole pattern. Next, via holes 72, 72 ... Are formed by development and etching, as shown in FIG.

As shown in FIG. 4 (i), electroless copper plating is performed to form metal layers 43, 43 ... In the via holes 72, 72 .... And the metal on the insulating layers 33, 33. To do.
After that, ashing is performed to roughen the surfaces of the insulating layers 33, 33 ... And the metal layers 43, 43. On this surface, Fig. 4 (j)
An insulating layer 34 of photosensitive polyimide is laminated as shown in FIG.

Thereafter, the same steps as those shown in FIGS. 3D, 3E, and 3F are performed. That is, the wiring pattern is exposed to form an opening, a second layer wiring is formed on the opening by electroless copper plating, and the surface is ashed. And Figure 4
As shown in (k), the insulating layer 35 of photosensitive polyimide is laminated to manufacture a multilayer wiring board.

The multi-layer wiring board thus formed is checked for continuity between same-layer wiring and different-layer wiring,
It was confirmed that no disconnection or short circuit occurred.

In this embodiment, Photonice "UR-3840" (manufactured by Toray Industries, Inc.) is used as the photosensitive resin, but "Promide 412" (manufactured by Ciba Gaiki Co., Ltd.) or "PL1045" ( Hitachi Chemical Co., Ltd.) or the like may be used.

[0023]

As described above, in the method of manufacturing a wiring board according to the present invention, since the metal wiring is formed by electroless plating, it can be formed by a simple operation with a small and inexpensive device with high dimensional accuracy. .. Further, since the metal wiring is formed on the surface of the photosensitive resin that has been subjected to the plasma treatment, the present invention exhibits excellent effects such as a large adhesive force between the photosensitive resin and the metal wiring.

[Brief description of drawings]

FIG. 1 is a flowchart showing a procedure for forming a multilayer wiring on a photosensitive resin according to the present invention.

FIG. 2 is a schematic cross-sectional view of a wiring board at a stage of forming a multilayer wiring on a photosensitive resin according to the present invention.

FIG. 3 is a schematic cross-sectional view of a wiring board at a stage of forming multilayer wiring on a photosensitive resin according to the present invention.

FIG. 4 is a schematic cross-sectional view of a wiring board at a stage of forming a multilayer wiring on a photosensitive resin according to the present invention.

FIG. 5 is a schematic cross-sectional view of a wiring board at a stage of forming a multilayer wiring on an insulating layer by a conventional method.

FIG. 6 is a schematic cross-sectional view of a wiring board at a stage of forming a multilayer wiring on an insulating layer by a conventional method.

FIG. 7 is a schematic cross-sectional view of a wiring board at a stage of forming a multilayer wiring on an insulating layer by a conventional method.

FIG. 8 is a schematic cross-sectional view of a wiring board at a stage of forming a multilayer wiring on an insulating layer by a conventional method.

[Explanation of symbols]

 11 Substrate body 21,33,34,35 Insulation layer 31 First insulation layer 32 Second insulation layer 41,42,43 Metal layer 51 Resist layer 61,62,63,64,65 Mask 71 Opening 72 Via hole

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05K 3/18 D 7511-4E

Claims (1)

[Claims] 1. A step of laminating a first photosensitive resin on a substrate and subjecting the surface of the first photosensitive resin to plasma treatment,
A second photosensitive resin is laminated on the first photosensitive resin, and an opening based on a wiring pattern is formed on the second photosensitive resin by a plasma-treated surface of the first photosensitive resin. And a step of forming a metal wiring in the opening by electroless plating, the method of manufacturing a wiring board.