JPH04274345A - Manufacture of multilayer wiring substrate - Google Patents

Abstract

PURPOSE:To prevent generation of pattern open by embedding a sensitive polyimide film having high solubility in viaholes by screen printing after forming viaholes of a sensitive polyimide film of a first insulating layer on a wiring pattern. CONSTITUTION:A sensitive polyimide film 3a is applied to the whole surface of a substrate 1, the surface of the sensitive polyimide film 3a of the upper part having a formed wiring pattern 2 is exposed to ultraviolet rays through a shielding glass mask, and the exposed substrate 1 is developed so as to form a first insulating layer having viaholes generated on the part not irradiated with ultraviolet rays. Before forming a second insulating layer, a sensitive polyimide film 4 having high solubility is imbedded in the viaholes formed in a first insulating layer by screen printing.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for manufacturing a multilayer wiring board, and in particular to a method for manufacturing a high-density multilayer wiring board for mounting large-scale integrated circuits used in electronic equipment such as computers. The present invention relates to a method of manufacturing a multilayer wiring board including a step of forming via holes for connection.

0002

[Prior Art] Conventionally, in manufacturing high-density multilayer wiring boards for mounting large-scale integrated circuits used in electronic devices such as computers, via holes connecting upper and lower conductor layers are formed according to the following process. It was done.

First, as shown in FIG. 3(a), a wiring pattern 2 is formed on a substrate 1.

Next, as shown in FIG. 3(b), a photosensitive polyimide film 3 is coated on the surface of the substrate 1 by spin coating, and low-temperature drying is performed at 70 to 80° C. for 40 to 60 minutes. conduct. In this state, the thickness of the photosensitive polyimide film 3 is 20 to 30 μm and has not been imidized yet.

Next, as shown in FIG. 3(c), the surface of the photosensitive polyimide film 3 determined in advance according to the wiring pattern design is exposed through a glass mask 5 that partially shields the surface of the photosensitive polyimide film 3. Only a portion is irradiated with ultraviolet light. After this, at 70-80℃, 90-120℃
Dry at low temperature for 1 minute.

Next, when the above substrate 1 is developed, it becomes as shown in FIG.
As shown in d), the photosensitive polyimide film 3 in the part not irradiated with ultraviolet rays is removed to form a via hole, which has a regular taper shape (the top surface of the hole is wide and the bottom surface is narrow). A via hall will be formed. The developer used at this time was Methylcellosolve, N.Methyl.
2. A mixture of pyrrolidone, methyl alcohol, etc. is used.

Next, when this patterned photosensitive polyimide film 3 is cured at 300 to 400° C., the photosensitive polyimide film 3 is imidized and a first insulating layer is formed.

[0008] In the above process, only one layer of the imidized photosensitive polyimide film 3 was formed, but for high-density multilayer wiring boards, this process is repeated to form two layers for electrical insulation. The above insulating layers are formed.

[0009]

[Problems to be Solved by the Invention] In the conventional method for manufacturing a multilayer wiring board as described above, after forming the first insulating layer,
When forming the insulating layer, if spin coating is performed so that the thickness is the same as that of the first insulating layer, the thickness of the second insulating layer will be 7.5 mm above the wiring pattern, as shown in FIG. 3(e).
is formed thicker than the thickness 6 of the first insulating layer, so
When the photosensitive polyimide film of the second insulating layer is exposed in the next step, since the film is thick, less ultraviolet rays are transmitted. Because the film is thick and transmits little ultraviolet rays, the development speed on the sides of the via hole is faster than the development speed in the depth direction of the via hole in the next development process, so the photosensitive polyimide film at the bottom of the via hole is removed. When it is done,
In the photosensitive polyimide film of the second insulating layer, as shown in FIG. 3(f), an inversely tapered via hole 8 is easily formed in which the top surface of the hole is narrow and the bottom surface is wide. When this inverted tapered via hole 8 is formed, the disadvantage is that in the process of connecting the upper and lower conductor layers, pattern open, which is the disconnection of the wiring pattern of the upper and lower conductor layers, is likely to occur due to the side surface of the inverted tapered via hole. have.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a multilayer wiring board that can form a normally tapered via hole and prevent pattern opening.

[0011]

[Means for Solving the Problems] The method for manufacturing a multilayer wiring board of the present invention includes (A) a first step of forming a wiring pattern on the board, (B) coating the photosensitive resin over the entire surface of the board. A film was applied, and ultraviolet rays were exposed through a shielding mask that shielded a part of the surface of the photosensitive resin film on which the wiring pattern was formed, and after exposure, the substrate was developed, and no ultraviolet rays were irradiated. a second step of forming a first insulating layer with a first via hole created in the part (C
) Applying a photosensitive resin film again over the entire surface of the substrate,
Ultraviolet rays are exposed again through a shielding mask that shields a part of the surface of the photosensitive resin film on which the wiring pattern is formed, and after exposure, the substrate is developed, so that no ultraviolet rays are generated in the portions that were not irradiated with ultraviolet rays. a third step of forming a second insulating layer having a second via hole. The first via hole is filled with a photosensitive resin film having a high dissolution rate.

0012

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the method for manufacturing a multilayer wiring board according to the present invention, and is a diagram showing a cross-sectional state of the multilayer wiring board in the order of progress of the steps.

The method for manufacturing a multilayer wiring board according to this embodiment includes a step of forming a wiring pattern 2 on a substrate 1, a photosensitive polyimide film 3a is applied over the entire surface of the substrate 1, and the wiring pattern 2 is formed. Ultraviolet rays are exposed through a glass mask 5 that shields a part of the surface of the upper photosensitive polyimide film 3a, and after exposure, the substrate 1 is developed, and a first layer having a via hole formed in a portion not irradiated with ultraviolet rays is formed. A process of forming an insulating layer, a process of embedding a photosensitive polyimide film 4 having a high dissolution rate into the via holes of the first insulating layer, and a process of recoating the photosensitive polyimide film 3b over the entire surface of the substrate 1 to form a wiring pattern 2. The upper photosensitive polyimide film 3
The substrate 1 is exposed again to ultraviolet light through the glass mask 5 that shields a part of the surface of b, and after the exposure, the substrate 1 is developed to form a second insulating layer having via holes formed in the parts that were not irradiated with the ultraviolet light. It consists of processes.

Next, a method for manufacturing the multilayer wiring board of this embodiment will be explained.

In FIG. 1, there are steps from the step of forming a wiring pattern 2 shown in FIG. 1(a) to the step of forming a first insulating layer by forming a via hole in the photosensitive polyimide film 3a, shown in FIG. 1(d). The steps up to this point are the same as in the prior art.

In the method for manufacturing a multilayer wiring board of this embodiment,
The following process is provided before the process of forming the second insulating layer. That is, as shown in FIG. 1(e), a photosensitive polyimide film 4 having a high dissolution rate is embedded in the via hole formed in the first insulating layer by screen printing, and then 70~
Low-temperature drying is performed at 80°C for 30 minutes.

After the above steps are the same as in the conventional case, as shown in FIG. 1(f), a photosensitive polyimide film 3b as a second insulating layer is applied by spin coating, and
Low-temperature drying is performed at ~80°C for 40-60 minutes. The photosensitive polyimide film 3b at this time also has a thickness of 20 to 30 μm, similar to the first layer photosensitive polyimide film 3a, as in the conventional case. In addition, as shown in FIG. 1(g), only a predetermined part of the surface according to the wiring pattern design is exposed to ultraviolet light through the glass mask 5, and low-temperature drying is performed at 70 to 80°C for 90 to 120 minutes. It will be done.

Next, development is carried out in the same manner as in the conventional case, but as shown in FIG. 2, immediately after the via hole in the photosensitive polyimide film 3b of the second insulating layer is opened, Since the photosensitive polyimide film 4 is developed, the development speed in the depth direction of the via hole is faster than before, and the development speed of the photosensitive polyimide film 3b on the side surface of the via hole is suppressed. Therefore, as shown in FIG. 1(h), a normally tapered via hole with good connectivity is formed.

In this manner, after forming the via holes of the photosensitive polyimide film 3a of the first insulating layer on the wiring pattern, the photosensitive polyimide film 4 having a high dissolution rate is buried in the via holes by screen printing, thereby forming the second insulating layer. Since the layer photosensitive polyimide film 3b is developed at the same time as the buried photosensitive polyimide film 4 which has a high dissolution rate, the development rate of the side surface of the via hole is suppressed, and a normally tapered via hole can be formed.

[0021]

As explained above, in the method for manufacturing a multilayer wiring board of the present invention, after forming via holes in the photosensitive polyimide film of the first insulating layer on the wiring pattern, By filling the via hole with screen printing, the photosensitive polyimide film of the second insulating layer is developed at the same time as the embedded photosensitive polyimide film, which has a high dissolution rate, so the development speed on the sides of the via hole is suppressed and the This has the effect that a tapered via hole can be formed, the connectivity of the via hole between the upper and lower conductor layers can be improved, and the occurrence of pattern open can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating an embodiment of the method for manufacturing a multilayer wiring board according to the present invention, and showing a cross-sectional state of the multilayer wiring board in the order of progress of the steps.

FIG. 2 is a state during the development process of the photosensitive polyimide film of the second insulating layer and the photosensitive polyimide film with a fast dissolution rate embedded in the via holes of the first insulating layer in the method for manufacturing the multilayer wiring board shown in FIG. FIG.

FIG. 3 is a diagram illustrating a conventional method for manufacturing a multilayer wiring board, showing the state of a cross section of the multilayer wiring board in the order of progress of the steps.

[Explanation of symbols]

1　　　　Substrate 2 Wiring pattern 3 Photosensitive polyimide film 4 Photosensitive polyimide film 5 Glass mask 6 Thickness of first insulating layer 7 Thickness of second insulating layer 8 Reverse tapered via hole

Claims (3)

[Claims] 1. (A) a first step of forming a wiring pattern on a substrate, (B) applying the photosensitive resin film over the entire surface of the substrate, and applying the photosensitive resin film to the top of the substrate where the wiring pattern is formed; A first insulator having a first via hole formed in a portion not irradiated with ultraviolet rays by exposing ultraviolet rays through a shielding mask that shields a part of the surface of the photosensitive resin film, and developing the substrate after exposure. The second step of forming a layer, (C
) Re-applying a photosensitive resin film over the entire surface of the substrate,
Ultraviolet rays are exposed again through a shielding mask that shields a part of the surface of the photosensitive resin film on which the wiring pattern is formed, and after exposure, the substrate is developed, so that no ultraviolet rays are generated in the portions that were not irradiated with ultraviolet rays. a third step of forming a second insulating layer having a second via hole. 1. A method for manufacturing a multilayer wiring board, comprising the step of embedding a photosensitive resin film having a high dissolution rate into the via hole of No. 1. 2. The method of manufacturing a multilayer wiring board according to claim 1, wherein the photosensitive resin is a photosensitive polyimide film. 3. The method of manufacturing a multilayer wiring board according to claim 1 and claim 2, wherein the first via hole is filled with the photosensitive resin film having a high dissolution rate by screen printing. manufacturing method.