JP2755019B2 - Method for manufacturing multilayer wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer wiring board, and more particularly to a method for manufacturing a multilayer wiring board based on a large ceramic substrate.

[0002]

2. Description of the Related Art A conventional multilayer wiring board used for an ultra-large computer or the like employs a so-called thick film method in which a conductive paste and an insulating paste are alternately printed on a ceramic substrate by a screen printing method and fired. However, in order to increase the density of component mounting, a so-called thin film method using photolithographic technology has been used, and in order to increase the signal transmission speed, it is necessary to lower the dielectric constant of the insulating layer. As a problem, an organic insulating film has been used as a material of the insulating film instead of the inorganic insulating film. As a material for the organic insulating film, high heat resistance is required, and thus polyimide is generally employed.

Further, in recent years, in order to simplify the formation of via holes for connecting the upper and lower conductor layers, a via hole can be formed by a photolithographic technique without using a photoresist. So-called photosensitive polyimide, which is obtained by imparting photosensitivity to polyimide, has been used.

[0004]

However, in recent multilayer wiring boards, in order to further increase the component mounting density, the size of the board is continually increased, and the number of layers to be stacked is also increasing. Tend to. For this reason, in the conventional photosensitive polyimide, the coefficient of thermal expansion is too large to be different from the coefficient of thermal expansion of the ceramic substrate, reaching the limit of use as an insulating film. Must be used.

However, polyimide having a small coefficient of thermal expansion is
Since a via hole must be formed using a photoresist, there is a problem that it takes time and effort to manufacture compared to a photosensitive polyimide that can form a via hole using a photolithographic technique. As the number increases, the difference increases. In addition, there is a problem in processing stability.

[0006]

According to a method of manufacturing a multilayer wiring board of the present invention, a conductor layer obtained by depositing gold or copper on a metal thin film formed on a ceramic substrate and an insulating layer of photosensitive polyimide are formed. Alternatingly forming via holes in the insulating layer, connecting the upper and lower conductor layers, removing the insulating layer of the photosensitive polyimide by etching, injecting polyimide having a low coefficient of thermal expansion and curing. Forming a new insulating layer.

[0007]

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

FIGS. 1 and 2 are sectional views showing an example of a multilayer wiring board manufactured by applying an embodiment of the present invention in the order of steps. FIG. 1 is a view showing the first half of the process, and FIG. FIG.

[0009] The present embodiment, first, as shown in FIG. 1 (a), the number 1000 appropriately <br/> assembly seen if not I titanium and chromium and palladium and copper by a sputtering method on the ceramic substrate 1 A metal thin film 2 having a thickness of Å is formed, and a photoresist 3 is applied thereon and dried. As the photoresist 3, a liquid positive type resist is used in order to obtain high resolution.

Next, as shown in FIG. 1B, the photoresist 3 is exposed to light using a predetermined mask (not shown) and developed to thereby correspond to the wiring pattern of the metal thin film 2. Exposing the part to be done.

Further, as shown in FIG. 1C, using the metal thin film 2 as an electrode, a conductor layer 4 is formed by depositing gold or copper on the metal thin film 2 exposed by an electroplating method. .

Next, as shown in FIG. 1D, the remaining photoresist is removed by using a dedicated stripper,
Further, using the conductor layer 4 as an etching mask, the metal thin film exposed by removing the photoresist is also removed. As an etching means, a dry etching method using an ion beam is used. Thus, the wiring pattern 9 having a desired shape can be formed on the ceramic substrate 1. In this series of steps, on the outer peripheral portion of the ceramic substrate 1,
A boundary wall 5 surrounding the wiring pattern 9 is formed.

Next, as shown in FIG. 1E, the ceramic substrate 1, the wiring pattern 9 and the boundary wall 5 are
A photosensitive polyimide varnish 6 is applied and dried.

Next, as shown in FIG. 1F, a photosensitive polyimide varnish 6 is formed using a predetermined mask (not shown).
After exposure to light and development, heat treatment is performed to form an insulating layer of polyimide film 7 having via holes for connecting upper and lower conductor layers.

By repeating the steps shown in FIGS. 1A to 1F as many times as necessary, a wiring pattern 9 and a polyimide film are formed on the ceramic substrate 1 as shown in FIG. 2A. 7 are alternately laminated in a multilayer.

Next, as shown in FIG. 2B, the polyimide film 7 is removed by etching. As an etching means, an etching method using oxygen gas plasma or an etching method using excimer laser is used. Even when the polyimide film 7 is completely removed in this manner, the wiring pattern 9 retains its shape because it is supported by the via 9a.

Next, as shown in FIG. 2C, a polyimide varnish having a low coefficient of thermal expansion is injected into the space from which the polyimide film has been removed, and heat treatment is performed to form an insulating layer 8.

[0018]

As described above, according to the method for manufacturing a multilayer wiring board of the present invention, a conductor layer of a metal thin film and an insulating layer of photosensitive polyimide are alternately formed on an insulating substrate to form a via on the insulating layer. After connecting the upper and lower conductor layers by forming holes, the photosensitive polyimide insulating layer is removed by etching, and then a polyimide having a low coefficient of thermal expansion is injected and cured to form a new insulating layer By doing
There is an effect that a multilayer wiring board using polyimide having a small coefficient of thermal expansion as an insulating layer can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a multilayer wiring board manufactured by applying one embodiment of the present invention in the order of steps, showing the first half of the steps.

FIG. 2 is a cross-sectional view showing an example of a multilayer wiring board manufactured by applying one embodiment of the present invention in the order of steps, and showing the latter half of the steps.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic substrate 2 Metal thin film 3 Photoresist 4 Conductive layer 5 Boundary wall 6 Photosensitive polyimide varnish 7 Polyimide film 8 Insulating layer 9 Wiring pattern 9a Via

Claims (2)

(57) [Claims] 1. A wiring pattern having a predetermined shape by applying a photoresist on a metal thin film formed on a ceramic substrate.
After exposing the portion corresponding to the photoresist , gold or copper is deposited thereon to form a conductor layer, and the photoresist is removed.
And dry etching the metal thin film by ion beam.
Forming a wiring pattern by removing the wiring pattern.
Apply a photosensitive polyimide varnish on the pattern and specify
Form form an insulating layer having a via hole by removing a part, Engineering from formation of the metal thin film to form the insulating layer
The process is repeated a predetermined number of times, and the metal thin film and the arrangement are repeated.
The insulation pattern by laminating the
The wiring patterns above and below the layer are
And connect the photosensitive polyimide insulating layer to an oxygen gas pump.
A method for manufacturing a multilayer wiring board, comprising: forming a new insulating layer by injecting and curing polyimide having a low coefficient of thermal expansion after being removed by etching using a plasma or an excimer laser . . 2. A photoresist is coated on a metal thin film formed by appropriately combining titanium, chromium, palladium, and copper on a ceramic substrate to form
After exposing the portion corresponding to the
The conductor layer is formed by depositing gold or copper on the
The metal thin film is treated with ion beam
Removed by light etching to form wiring pattern
And a photosensitive polyimide varnish on the wiring pattern.
Form of the coating to form form the insulation <br/> edge layer having a via hole by removing a predetermined portion, the insulating layer from the formation of the metal thin film
The steps up to formation are repeated a predetermined number of times, and the metal thin film and
And the arrangement pattern and the insulating layer are laminated in multiple layers.
The wiring pattern above and below the insulating layer
The photosensitive polyimide insulating layer.
A multilayer wiring board comprising forming a new insulating layer by injecting and curing polyimide having a low coefficient of thermal expansion after removing by etching with oxygen gas plasma or excimer laser. Manufacturing method.