JPH02148888A - Multilayer interconnection substrate - Google Patents

Abstract

PURPOSE:To improve machinability of a second connecting window and to prevent a remaining part of etching by forming the thickness of a second interlayer insulating film thicker than the thickness of a first interlayer insulating film. CONSTITUTION:A heat resisting resin varnish which is used for forming a first interlayer insulating film 3 is applied in a spinning mode under the conditions of 1,000 rpm and 30 seconds. Thereafter, a second connecting window 4a is formed. At this time, the film thickness at a part of the second connecting window 4a is 5.9 mum. The depth of a first connecting window 3a is 2.2 mum. as a result of the hardening and contraction of the first interlayer insulating film 3 due to heating and hardening. Namely, the thickness of a second interlayer insulating film 4 is made thicker than the thickness of the first interlayer insulating film 3. Therefore, dispersion in thickness of the second interlayer insulating film 4 at a part where the second connecting window 4a is provided becomes less. At the same time, in the step for forming the second connecting window 4a, the etching depth becomes deeper than the depth of the first connecting window inevitably. Dispersion in machinability of the second window 4a can be suppressed, and the remaining part of etching can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multilayer wiring board, and more particularly to a multilayer wiring board including an interlayer insulating layer made of a heat-resistant resin layer with a two-layer laminated structure.

[Conventional technology]

Conventionally, this kind of multi-layered tablet! There is one shown in FIG. 3 as an M substrate. That is, a first wiring layer 2 is formed on an insulating substrate 1, and a polyamic acid (8) solution is applied thereon using a spin cord method, and is semi-cured by heat treatment at 120 to 150°C. Furthermore, a first connection window 3a is provided at a predetermined position.
After opening, the first interlayer insulating film 3 made of a heat-resistant resin layer is formed by heating and curing at a temperature of 200° C. or higher.

Further, on this, a second interlayer insulating film 4 made of a heat-resistant resin layer formed in the same manner as the first interlayer insulating film 3 is formed, and a second interlayer insulating film 4 is formed at the same position as the first connection window 3a. Connection window 4a
has been established. Thereafter, these are heat treated at a temperature of 300 to 400°C for final curing.

Then, a second wiring layer 5 is formed on these interlayer insulating films 3 and 4, and a first wiring N2 is formed through the connection windows 3a and 4a.
electrically connected to.

[Problem to be solved by the invention]

In the above-mentioned conventional multilayer wiring board, since the heat-resistant resin layers constituting the first and second interlayer insulating films 3 and 4 are formed under the same conditions, etching is not required when processing the second connection window 4a. There is a problem in that the electrical connection between the wiring layer 2 and the second wiring layer 5 of the cylinder 1 becomes unstable as a result.

That is, as shown in FIG. 4(a), the first interlayer insulating film 3 formed on the insulating substrate 1 on which the first wiring layer 2 is formed is formed by coating by the spin code method. The film thickness T1 in the portion where the connection window 3a is provided, that is, on the first wiring layer 2, is thinner than the film thickness T in other portions.

On the other hand, as shown in FIG. 4(b), since the second interlayer insulating film 4 formed on the upper side is similarly formed by coating by the spin code method, the portion where the second connection window 4a is provided, that is, the The film thickness T2 in one connection window 3a is thicker than the film thickness T in other parts.

Therefore, if the thickness of the first interlayer insulating film is equal to or greater than the thickness of the second interlayer insulating film, the conditions for forming the second connection window 4a are the same as the conditions for forming the first connection window 3a. If etching is performed, it becomes difficult to etch the entire thickness of the second connection window 4a, and as a result, the second interlayer insulating film 4
A portion of is left in the first connection window 3a. This results in
The surface of the first wiring layer 2 is not exposed, and the electrical connection with the second wiring layer 5 becomes unstable.

The present invention prevents etching residue on the second interlayer insulating film,
An object of the present invention is to provide a multilayer wiring board that makes it possible to obtain a suitable electrical connection between upper and lower wiring layers.

[Means to solve the problem]

The multilayer wiring board of the present invention includes a first wiring layer formed on an insulating substrate, and a first interlayer insulating film made of a heat-resistant resin layer having a first connection window on a part of the first wiring layer. and a second interlayer insulating film made of a heat-resistant resin layer having a second connection window at the same position as the first connection window; a second wiring layer that is connected to the
It is formed thicker than the interlayer insulating film.

[Effect]

In the above configuration, the variation in the thickness of the second interlayer insulating film within the first connection window of the first interlayer insulating film can be reduced.
The workability of the second connection window is improved to prevent etching residue.

〔Example〕

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

FIG. 1 is a sectional view of a first embodiment of the present invention.

A first wiring layer 2 is formed on the surface of the insulating substrate 1 using known film forming techniques such as sputtering and photoetching.

On the insulating substrate 1 and the first wiring layer 2, a heat-resistant resin face (e.g., viscosity: LOPs, non-volatile content: 1 non-volatile content, using Vaginone as a solvent) was spin-coated at 2000 rpm for 30 seconds, and then heated to 135°C. Perform curing treatment for 20 minutes. Next, a positive photoresist is spin-coated, a resist hake is performed at around 90°C, and after exposure through a predetermined photomask, a positive resist developer (for example, Tokyo Ohka NMD-3) is applied. According to
A first connection window 3a is formed. Note that at this point, the film thickness at the first connection window 3a was 2.8 μm. Subsequently, heat curing treatment is performed for 30 minutes in N2 at 200° C. to form a first interlayer insulating film 3 made of a heat-resistant resin layer and having a first connection window 3a.

Subsequently, after spin-coating the heat-resistant resin varnish used for forming the first interlayer insulating film 3 at 1000 rpm for 130 seconds, the second connection window 4a is formed by the same process as the formation of the first connection window 3a. Perform formation. At this point, the film thickness at the second connection window 4a is 5.9 μm, and the depth of the first connection window 3a is determined by the hardening of the first interlayer insulating film 3 by the heat hardening process described above. As a result of shrinkage, it became 2.2 μm.

Subsequently, a heat curing process is performed for 30 minutes in N2 at 200° C. to form a second interlayer insulating film 4 made of a heat-resistant resin layer and having a second connection window 4a.

Further, a final curing treatment is performed for 60 minutes in N2 at 350° C. to form a glabellar insulating film made of a heat-resistant resin layer having a double-layered structure with double-connected windows. The film thickness of the glabellar insulating film after the final curing treatment was 6.0 μm.

Thereafter, a second wiring layer 5 is formed by a process similar to that of forming the first wiring layer 2, and both wiring layers 2.5 are electrically connected to each other through the double connection window.

According to this configuration, since the thickness of the second interlayer insulating film 4 is formed to be larger than the thickness of the first interlayer insulating film 3, the second interlayer insulating film 4 is formed to have a larger thickness than the first interlayer insulating film 3, so that the second interlayer insulating film 4 is formed to have a larger thickness than the first interlayer insulating film 3. Variations in the thickness of the film 4 are reduced.

At the same time, the process of forming the second connection window 4a is necessarily a process of etching deeper than the process of forming the first connection window 3a, making it possible to suppress variations in workability of the second connection window 4a. , the etching residue can be prevented. Therefore, the electrical connection between the first wiring layer 2 and the second wiring layer 5 can be made stable.

FIG. 2 is a sectional view of Example 2 of the present invention.

A first wiring layer 2 is formed on an insulating substrate 1 by a process similar to that of the first embodiment, and a 100μ
A first interlayer insulating film 3 made of a heat-resistant resin layer having a first connection window 3a with a diameter of m is formed.

Further, after spin coating and curing a heat-resistant resin varnish under the same conditions as in the first embodiment, a second connection window 4 with a diameter of 60 μm is placed in the center of the first connection window 3a with a diameter of 100 μm.
form a. Thereafter, an interlayer insulating film having a double laminated structure having double connection windows is formed using the same process as in the first embodiment. A second wiring layer 5 is formed on this.

In this embodiment, since the second connection window 4a is processed only on the flat part inside the first connection window 3a, the second connection window 4a is
This has the advantage that variations in workability of the connection windows 4a are further reduced.

In each of the above embodiments, polyimide resin is used as an example of the material of the heat-resistant resin layer constituting the interlayer insulating film.
The resin material used in the present invention is not necessarily limited to polyimide as long as it is a thermosetting heat-resistant resin, and for example, polyamide resin or organosiloxane resin can also be used.

Further, the present invention is not limited in any way to the number of wiring layers, and the present invention can be applied to a wiring board having three or more layers.

[Effects of the Invention] As explained above, in the present invention, since the second interlayer insulating film is formed thicker than the first interlayer insulating film, the first connection of the first interlayer insulating film is It is possible to reduce the variation in the thickness of the second interlayer insulating film within the window, improve the workability of the second connection window within the first connection window, and prevent the remaining etching of the second N interlayer insulating film. This has the effect of improving the electrical connection characteristics between the first wiring layer and the second wiring layer.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the first embodiment of the present invention, FIG. 2 is a cross-sectional view of the second embodiment of the present invention, FIG. (a) and (b) are process cross-sectional views for explaining conventional problems. DESCRIPTION OF SYMBOLS 1... Insulating substrate, 2... First wiring layer, 3... First interlayer insulating film, 3a... First connection window, 4... Second
Interlayer insulating film, 4a... second connection window, 5... second wiring layer. Figure 1 Figure 2

Claims (1)

[Claims] 1. A first wiring layer formed on an insulating substrate, a first interlayer insulating film made of a heat-resistant resin layer having a first connection window on a portion of the first wiring layer, and the first interlayer insulating film. a second interlayer insulating film formed on the heat-resistant resin layer and having a second connection window at the same position as the first connection window;
and a second wiring layer electrically connected to the first wiring layer through a second connection window, the second interlayer insulating film being thicker than the first interlayer insulating film. A multilayer wiring board characterized by forming a multilayer wiring board.