JPH0498891A - Manufacture of multilayer wiring board - Google Patents

Abstract

PURPOSE:To protect a wiring pattern against disconnection by a method wherein the baking of a filler containing polyimide film is carried out in such a manner that 1/2-1/3 of the overall baking is performed before the film is exposed to light and the rest of the overall baking is carried out after the exposure of the film. CONSTITUTION:A lower wiring pattern 2 is formed on a board 1 (a). In succession, a filler containing polyimide film 3 is applied onto the whole surface of the board 1, which is dried up in an oven at a temperature (b). The film 3 is irradiated with ultraviolet rays S through a glass mask 6 which is partially shield so as to enable the film 3 to be irradiated with light energy (c). Then, the board 1 is dried up at a low temperature in an oven. By this low temperature drying of the board after exposure, a crosslinking reaction is accelerated inside the exposed part of the polyimide film 3 to be spread to the unexposed part. It is preferable that this low temperature drying is carried out two or three times as intense in baking as that performed before exposure (d). Then, when the board is developed, a positively tapered viahole 5 is formed through the effect of low temperature drying. Lastly, the, patterned filler containing polyimide film 3 is turned into the film 3 of imide by curing (e).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a multilayer wiring board, and in particular to a method for manufacturing a multilayer wiring board, particularly for large-scale integrated circuits (for use in electronic devices such as computers).
The present invention relates to a method for manufacturing a multilayer wiring board including a step of forming via holes for connecting upper and lower conductor layers in a high-density multilayer wiring board for mounting (LSI).

[Conventional technology]

Among conventional methods for manufacturing multilayer wiring boards, large-scale integrated circuits (LS) for use in electronic devices such as computers
I) In the method for manufacturing a high-density multilayer wiring board for mounting, a method for forming via holes for connecting upper and lower conductor layers will be described with reference to the drawings.

FIGS. 2(a) to 2(d) are cross-sectional views showing an example of a multilayer wiring board in the process of being manufactured by a conventional multilayer wiring board manufacturing method.

The conventional method for manufacturing a multilayer wiring board includes a first step of forming a metal wiring pattern 2 on a substrate 1 shown in FIG. 2(a), and a step of forming a metal wiring pattern 2 on the wiring pattern 2 shown in FIG. A second step of forming a photosensitive filler-containing polyimide film 3 over the entire surface of the substrate 1 by spin coating, and a step shown in FIG.
A third step of drying the filler-containing polyimide film 3 in an oven at a low temperature shown in c), and a fourth step of irradiating the filler-containing polyimide film 3 with ultraviolet rays through a glass mask 6 that shields a predetermined portion. The filler-containing polyimide film 3 irradiated with ultraviolet rays shown in FIG. 2(d) is developed and the filler-containing polyimide film 3 in the portion corresponding to the shielded portion is removed to form a reverse tapered via hole 4.
The manufacturing method included a fifth step of curing the filler-containing polyimide film 3 to imidize it.

[Problem to be solved by the invention]

In the conventional multilayer wiring board manufacturing method described above, the second
As shown in the figure, the film thickness of the filler-containing polyimide film 3 is 2
Because the film is thick, ranging from 0 μm to 30 μm, the ultraviolet rays do not pass through to the bottom of the filler-containing polyimide film 3 during exposure, as shown in FIG. Since it is formed in a reverse tapered shape (the top of the hole is narrow and the bottom is wide) (reference number 4a),
In the next step of forming a metal wiring pattern, the side surface 4a of the inversely tapered via hole 4 and the upper layer wiring pattern 2 are likely to be cut, resulting in a so-called pattern oven. Another drawback is that if the time from spin coating to development is long, cracks are likely to occur during development due to moisture absorption.

[Means to solve the problem]

The method for manufacturing a multilayer wiring board of the present invention includes a first step of forming a metal wiring pattern on the board, and spin coating a photosensitive filler-containing polyimide film over the entire surface of the board on the metal wiring pattern. a second step of drying the filler-containing polyimide film at a low temperature in an oven, and irradiating ultraviolet rays through a glass mask that shields predetermined portions of the filler-containing polyimide film. a fifth step of drying the filler-containing polyimide film at a low temperature two to three times stronger than the third step, and developing the filler-containing polyimide film irradiated with ultraviolet rays to develop the shielded portion. and a sixth step of removing the filler-containing polyimide film in a corresponding portion to form a via hole, and curing the filler-containing polyimide film to imidize the filler-containing polyimide film.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) to 1(e) are cross-sectional views showing an example of a multilayer wiring board manufactured according to an embodiment of the present invention in the order of steps.

In this embodiment, as shown in FIG. 1(a), first, a lower wiring pattern 2 is formed on a substrate 1.

Next, as shown in FIG. 1(b), a filler-containing polyimide film 3 is applied over the entire surface of the substrate 1 by spin coating and dried at a low temperature in an oven. In this state, the film thickness of the filler-containing polyimide film 3 is 20 μm to 3 μm.
0 Atm, it has not yet been imidized, and the low-temperature drying temperature is 70° C. to 80° C. and the time is 40 minutes to 60 minutes, which is a soft baking state.

Next, as shown in FIG. 1(c), ultraviolet light S to expose. In this state, ultraviolet ray S is 20 μm to 30 μm for filler-containing polyimide M3.
Because of the thickness, ultraviolet rays do not penetrate to the bottom of the filler-containing polyimide film 3.

Next, as shown in FIG. 1(d), it is dried at low temperature in an oven. By drying at a low temperature after this exposure, the crosslinking reaction in the exposed areas of the filler-containing polyimide film 3 is promoted and diffused to the unexposed areas. This low-temperature drying is 2 times higher than the low-temperature drying before exposure.
The cross-linking reaction is easily promoted by ~3 times stronger baking, and 7
Baking at 0°C to 80°C for 120 to 180 minutes is best.

Next, as shown in FIG. 1(e), when developed, the crosslinking reaction is promoted due to the effect of low-temperature drying after exposure and is diffused to the bottom of the filler-containing polyimide film 3.
A positively tapered via hole 5 having a positive taper (reference numeral 5a) with excellent connectivity is formed. Finally, the filler-containing polyimide film 3 patterned as described above is cured at 300° C. to 400° C. to imide.

〔Effect of the invention〕

As explained above, in the method for manufacturing a multilayer wiring board of the present invention, by setting the baking ratio of the filler-containing polyimide film before and after exposure to 1=(2 to 3), the crosslinking reaction after exposure is promoted, and development There is an effect that a normally tapered via hole can be formed through the process, and therefore, it is possible to prevent the occurrence of a pattern open. Baking after exposure also has the effect of preventing moisture absorption and preventing the occurrence of cracks.

[Brief explanation of the drawing]

FIGS. 1(a) to (e) are cross-sectional views showing an example of a multilayer wiring board manufactured according to an embodiment of the present invention in the order of steps, and FIGS. 2(a) to (d) are cross-sectional views of a conventional multilayer wiring board. FIG. 3 is a cross-sectional view showing an example of a multilayer wiring board in the process of being manufactured by the manufacturing method of FIG. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Wiring pattern, 3... Polyimide film containing filler, 4... Reverse taper via hole, 5... Positive taper via hole, 6... Glass mask, 7...・Transmission of ultraviolet rays, 8...Promotion of crosslinking reaction.

Claims (1)

[Claims] a first step of forming a metal wiring pattern on the substrate;
a second step of forming a photosensitive filler-containing polyimide film over the entire surface of the substrate on the metal wiring pattern by a spin coating method; and a third step of drying the filler-containing polyimide film at a low temperature in an oven. and a fourth step of irradiating ultraviolet rays through a glass mask that shields a predetermined portion of the filler-containing polyimide film.
a fifth step of drying the filler-containing polyimide film at a low temperature two to three times stronger than the third step, and developing the filler-containing polyimide film irradiated with the ultraviolet rays to correspond to the shielded portion. A method for manufacturing a multilayer wiring board, comprising the steps of: removing a portion of the filler-containing polyimide film to form a via hole; and curing the filler-containing polyimide film to imidize it.