JP2644847B2 - Multilayer wiring board and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a multilayer wiring board having an LSI mounted thereon and used for an electronic computer and the like and a method of manufacturing the same. The present invention relates to a multilayer wiring board suitable for solving the problem and a manufacturing method thereof.

[Conventional technology]

In a multilayer wiring board in which wiring layers and insulating layers are alternately stacked, a convex step occurs due to the wiring layer formed on the insulating layer. On the other hand, a concave step occurs in a through-hole portion for connecting the wiring layers. 2. Description of the Related Art As the accuracy and function of a wiring board become higher and higher, it is required to increase the aspect ratio of wiring, increase the thickness of an insulating layer, and increase the number of wiring layers.
As a result, the level difference becomes large, and it becomes difficult to form the wiring layer and the through hole with high precision.

For example, Japanese Patent Application Laid-Open No. 59-227140 proposes a method for eliminating a step in an insulating layer. In the present invention, a photoresist layer is applied on an interlayer insulating layer having a step formed on a lower wiring layer, an opening of the photoresist layer on the step is formed, and a step portion of the interlayer insulating layer in the opening is formed. After removing the photoresist layer by wet etching and removing the photoresist layer, a new interlayer insulating layer is formed on the interlayer insulating layer.

[Problems to be solved by the invention]

The above-described prior art employs a method of eliminating a step by performing wet etching of an insulating layer using a mask made of a photoresist layer. Therefore, many steps such as coating, drying, exposure, development, post cure, wet etching, and photoresist stripping of the photoresist layer are required. In addition, if a mask displacement or a defect due to over-etching is found after wet etching, it is difficult to selectively remove the planarization insulating layer.
It was difficult to correct the defect.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer wiring board which solves such problems, has a small number of steps, is easy to repair defects, and can easily eliminate steps caused by wiring layers and through holes, and a method of manufacturing the same. Is to do.

[Means for solving the problem]

The above object is to form an insulating layer having photosensitivity on the surface of the substrate where the step is formed by the through hole and the wiring layer so that the step is filled, and expose and develop the insulating layer.
Use a photosensitive insulating layer that can be selectively removed from the insulating layer by forming a new insulating layer after removing the insulating layer on the convex wiring layer and by a certain method. Can be achieved by

That is, in order to achieve the above object, the present invention provides a multilayer wiring board formed by alternately laminating a wiring layer and an insulating layer on a substrate, wherein the multilayer wiring board is formed on a lower wiring layer. And a wiring pattern on the first insulating layer formed on the first insulating layer and electrically connected to a lower wiring through a side surface of the through hole. A wiring layer; a second insulating film layer on the first insulating layer and on the through hole, the surface of which is substantially the same height as the surface of the wiring pattern;
And a third insulating film layer having a substantially flat surface formed on the insulating film layer and the wiring pattern.

Also, a method for manufacturing a multilayer wiring board in which wiring layers and insulating layers are alternately stacked on a substrate is described by forming a first insulating layer on a lower wiring layer, and forming a through hole in the first insulating layer. To expose a desired portion of the lower wiring layer, and to form a wiring pattern by forming a conductive film on the side surfaces of the exposed lower wiring and through holes and the first insulating layer to form a wiring pattern. Is formed, and a photosensitive insulating material layer is formed by applying a photosensitive insulating material on the wiring layer. The photosensitive insulating film layer is exposed and developed to expose the upper portion of the wiring pattern except for the upper portion of the through hole. Removing the photosensitive insulating film layer, heat-treating the non-removed photosensitive insulating film layer to make the surface of the photosensitive insulating film layer almost the same height as the surface of the wiring pattern from which the photosensitive insulating film layer has been removed,
A second insulating film layer is formed on the heat-treated photosensitive insulating film layer and the wiring pattern whose surface heights are substantially the same.

(Operation)

In the present invention, the photosensitive insulating layer is formed on the surface of the substrate having the step by the wiring layer and the through hole so as to have a thickness enough to fill the step. At this time, the photosensitive insulating layer is formed thicker in the through-hole portion recessed from the periphery than in the other portions, and the recessed step in the through-hole portion is eliminated.
Next, by exposing and developing the photosensitive insulating layer, the convex photosensitive insulating layer on the wiring layer is selectively removed, so that the bumps of the wiring layer can be eliminated.

If a defect is found at this time, the photosensitive insulating layer is selectively removed using a predetermined etching solution or stripping solution, and a new photosensitive insulating layer is formed, so that correction can be easily performed. Can be.

Thereafter, a new insulating layer is formed to a predetermined thickness, and after performing through-hole processing, an upper wiring layer is formed. The above steps are repeated to form the required number of multilayer wiring boards.

Thus, in the present invention, instead of the photoresist process,
Since the photosensitive insulating layer is used, the number of steps can be reduced, and defects can be easily corrected in the planarization step.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First
5A to 5E are process cross-sectional views illustrating a method for manufacturing a multilayer wiring board according to one embodiment of the present invention.

As shown in FIG. 1 (a), for example, on a substrate 1 such as a ceramic substrate or a thick film multilayer wiring board, for example, a PIQ (trade name) manufactured by Hitachi Chemical Co., Ltd. is made uniform by a spinner. After spin-coating, heat treatment is performed to form an interlayer insulating layer 2 made of a polyimide film, and through holes 3 are formed in the interlayer insulating layer 2 by an ordinary photoetching process. Next, a conductor layer made of copper or copper and chromium is formed on the interlayer insulating layer 2 by an evaporation method, and is formed as a wiring layer 4 by a normal photoetching process. At this time, a concave portion 5 is formed on the through-hole portion 3.

Next, as shown in FIG. 2B, for example, Photo-Pal (trade name) manufactured by Hitachi Chemical Co., Ltd.
Is spin-coated on the entire surface by a spinner, and then heat-treated at 85 ° C. for 30 minutes to form a photosensitive insulating layer 6. At this time, as shown in the figure, the photosensitive insulating layer 6 is formed thicker in the concave portion 5 on the through-hole portion than in other portions.

Next, as shown in FIG. 2C, the photosensitive insulating layer 6 is exposed and developed using a photomask, and the photosensitive insulating layer 6 on the wiring layer is removed. At this time, if a defect is found in the planarization due to a mask displacement or the like, by performing ultrasonic cleaning in N-methyl-2-pyrrolidone at 70 ° C.
The photosensitive insulating layer 6 can be selectively removed.

Next, heat treatment at 200 ° C. for 30 minutes and at 350 ° C. for 60 minutes are performed in a nitrogen stream to form the photosensitive insulating layer 6 into a planarized insulating layer 7 made of a polyimide film shown in FIG. .

Next, as shown in FIG. 4E, a new interlayer insulating layer 8 is formed.
To form Thereafter, the above steps are repeated until the required number of layers is reached,
A multilayer wiring board is formed.

〔The invention's effect〕

As described above, according to the present invention, a step due to a wiring layer on an interlayer insulating layer and a through hole can be eliminated in a smaller number of steps as compared with a step using a photoresist, and defects at the time of planarization can be eliminated. Since the correction is easy, a highly reliable, high-performance multilayer wiring board can be realized.

[Brief description of the drawings]

1 (a) to 1 (e) are cross-sectional views showing a method for manufacturing a multilayer wiring board according to one embodiment of the present invention. 1 ... board such as thick film multilayer wiring board, 2 ... interlayer insulating layer, 3 ...
Through-hole, 4 ... wiring layer, 5 ... recess in through-hole part, 6 ... photosensitive insulating film, 7 ... planarization insulating layer, 8 ... upper interlayer insulating layer.

Continued on the front page (72) Inventor Fumio Kataoka 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Hitachi, Ltd.Production Technology Laboratory (72) Inventor Naka Naka, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi, Ltd. (56) References JP-A-59-74608 (JP, A) JP-A-62-266540 (JP, A)

Claims (2)

(57) [Claims] 1. A method for manufacturing a multilayer wiring board comprising alternately laminating wiring layers and insulating layers on a substrate, comprising: forming a first insulating layer on a lower wiring layer; A through hole is formed in the insulating layer to expose a desired portion of the lower wiring layer, and a conductive film is formed on the exposed lower wiring, the side surface of the through hole, and the first insulating layer. Forming a wiring pattern, forming a wiring layer, applying a photosensitive insulating material on the wiring layer to form a photosensitive insulating film layer, exposing and developing the photosensitive insulating film layer to form the through hole; Removing the photosensitive insulating film layer above the wiring pattern excluding the upper portion, and heat-treating the non-removed photosensitive insulating film layer so that the photosensitive insulating film layer removes the surface of the photosensitive insulating film layer The height of the wiring pattern is substantially the same as that of the surface of the wiring pattern. Forming a second insulating film layer on the heat-treated photosensitive insulating film layer and the wiring pattern. 2. A multilayer wiring board comprising a wiring layer and an insulating layer alternately laminated on a substrate, wherein a through hole is formed on a lower wiring layer and a desired portion of the lower wiring layer is formed on the lower wiring layer. A first insulating layer on which a wiring pattern is formed on the first insulating layer and electrically connected to the lower wiring via a side surface of the through hole; A second insulating film layer on the first insulating layer and on the through hole, the surface of which is substantially the same in height as the surface of the wiring pattern; A multilayer wiring board formed by laminating an insulating film layer and a third insulating film layer having a substantially flat surface on the wiring pattern.