JPH03173497A - Multilayer wiring board and manufacture thereof - Google Patents

Abstract

PURPOSE:To quicken machining, and to improve accuracy and increase density easily by forming a connecting hole for connecting a circuit pattern to an insulating layer by using an excimer laser. CONSTITUTION:A signal line 14 is shaped onto a polyimide film 11, the upper section of the signal line 14 is coated with a polyimide resin, and a polyimide layer 16 is formed through curing. The specified position of the layer 16 is irradiated with an excimer laser 18, thus forming a via hole 20. The solution of ethyl alcohol 22, etc., is sprayed repeatedly against the via hole 20, and a reaction product shaped in the via hole 20 is removed. An Ni layer 26 and a copper layer 28 are formed, a photo-resist layer 30 is shaped onto the layer 28, and a second signal line 32 is shaped through etching. Con sequently, the signal lines 14, 32 acquired are connected suitably by the via hole 20. Accordingly, machining is accelerated, and accuracy can be improved and density increased easily.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a multilayer wiring board applied to high-density IC packages, etc., and a method for manufacturing the same, particularly in which a copper thin film is applied to the circuit pattern and a polyimide is applied to the insulating layer. The present invention relates to a multilayer wiring board and a method for manufacturing the same.

<Prior Art> As the density of IC packages and the like increases, the multilayer wiring boards applied thereto are also required to have higher densities.

As a high-density wiring board corresponding to this, copper-polyimide substrates are attracting attention in place of conventional printed wiring boards and ceramic substrates.

This copper-polyimide substrate uses polyimide, which has a low dielectric constant of 3 to 3.5, as an insulating layer, so that the delay time of electrical signals can be shortened.

- Since copper, which has the second lowest electrical resistance after gold, is used as a conductor, sufficient conductivity can be ensured even when the wiring is miniaturized.

■ Since polyimide is used as the insulating layer, a thick insulating layer can be easily obtained and the wiring capacitance can be reduced.

■ It is possible to apply photolithography technology to the formation of wiring patterns, so there are very few restrictions on microfabrication.

It has the following advantages. Furthermore, since polyimide has superior workability compared to ceramics, it is easier to change the design.

By the way, when applying such a copper-polyimide board to a multilayer wiring board, via holes for connecting circuit patterns to be wired across the polyimide insulating layer, and electrode pins and circuit patterns are formed on the polyimide insulating layer. Although it is necessary to create connection holes such as through holes for connection, processing of this polyimide layer has the problem that the process is complicated and takes time.

<Problems to be Solved by the Invention> Etching is generally applied to form connecting holes in a polyimide layer in a copper-polyimide substrate, but when processing polyimide by wet etching, it is difficult to use a strong alkaline solution such as hydrazine. Because it is necessary to apply
There is a problem with workability. Moreover, hydrazine also has the problem of being highly toxic.

Further, high-density multilayer wiring boards require highly accurate connecting holes, but wet etching causes side etching, making it difficult to obtain highly accurate connecting holes.

On the other hand, polyimide is often processed by dry etching, but since both photoresist and polyimide are organic materials, there is no selectivity in the etching rate, and ordinary photoresists cannot be applied.

Therefore, first, an inorganic layer such as SiO□ is formed on a polyimide layer, and this inorganic layer is patterned by photolithography using reactive ion etching, etc., and then O2 plasma etc. are applied using this patterned inorganic layer as a mask. It is necessary to etch the polyimide layer by etching, which is very time-consuming. Moreover, the etching speed of polyimide using 02 plasma etc. is 0.2 μs/mi.
There is also the problem that etching takes time.

An object of the present invention is to solve the problems of the prior art as described above, by applying a multilayer wiring board using an insulating organic material, especially a copper-polyimide board, which can be processed quickly and easily, and with high precision. An object of the present invention is to provide a multilayer wiring board capable of increasing density and a method for manufacturing the same.

Means for Solving the Problems> To achieve the above object, the present invention provides a multilayer wiring board in which an insulating organic material is applied as an insulating layer, and a circuit pattern formed on the insulating layer by an excimer laser. Provided is a multilayer wiring board characterized by having connection holes for connection.

Another aspect of the present invention is that when manufacturing a multilayer wiring board using an insulating organic material as an insulating layer, connecting holes for connecting circuit patterns are formed by irradiating a predetermined position of the insulating layer with an excimer laser. A method of manufacturing a multilayer wiring board is provided.

Moreover, it is preferable that the insulating organic substance is various polyimide resins.

Further, it is preferable that the conductor forming the circuit pattern is copper.

Further, the excimer laser may be XeCj2” or Kr
Preferably, it is an excimer laser applying a gas of F''.

The present invention will be explained in detail below.

1 to 6 are schematic cross-sectional views showing an example of the method for manufacturing a multilayer wiring board of the present invention and the multilayer wiring board of the present invention manufactured by the method.

FIG. 1 is a schematic cross-sectional view when a first signal line 14 made of copper and forming a circuit pattern is formed by photoetching on a polyimide film 12 forming an insulating layer.

In the present invention, an insulating organic substance is applied to the insulating layer. As the insulating organic material that can be applied to the present invention, any insulating organic material that is used in ordinary multilayer wiring boards, such as polyimide resin and epoxy resin, can be used. For these reasons, an insulating organic material made of polyimide resin is particularly suitable.

In addition, even if the insulating organic substance applied to the present invention is processed into a film or sheet, it can be applied in liquid form or dissolved in various solvents by a known method.
It may be something that hardens.

Further, the conductive material forming the circuit pattern is not limited to copper as described above, and various known materials such as gold, silver, aluminum, and alloys thereof can be used. However, in terms of cost, electrical resistance, etc., copper is most preferred.

There is no particular limitation on the method of forming the circuit pattern, and in addition to photolithography techniques, any of the various methods of forming circuit patterns that are applied to the production of normal multilayer wiring boards can be applied.

Next, in the illustrated example, as shown in FIG. 2, a polyimide resin is applied onto the polyimide film 12 and the first signal line 14 using a spin cord, and is cured to form a polyimide layer 16 constituting an insulating layer. . Note that the method for applying the polyimide resin and the like is not limited to the above-mentioned spin cord, and any known method such as roll coating or dip coating can be applied.

Next, as shown in FIG. 3, a pie hole 20 is formed in a predetermined position of the polyimide layer 16 by irradiating an excimer laser 18 using KrF'.

As is well known, an excimer laser (excimer laser) is a laser that uses diatomic molecules that exist only in an excited state. The present invention has discovered that insulating organic materials, especially polyimide resins, can be suitably processed using this excimer laser, and by using this, processing can be done quickly and easily, and it is also possible to increase the density with high precision. This was achieved by discovering that it was possible to easily produce a multilayer wiring board.

The excimer laser 18 to be applied is not particularly limited, and in addition to the one using KrF'' described above, XeC1'', Ar
Discharge rare gas excimer laser that applies F” etc., Hg2
Any known excimer laser can be used, such as an excimer laser using %Xe2 or Ar2'' gas.

In particular, KrF'X
An excimer laser applying eCj2'' gas is preferably applied.

The output (energy density) of the excimer laser when processing an insulating layer with such an excimer laser 18 is not particularly limited, and may be set appropriately depending on the material, thickness, etc. of the insulating layer, but usually the energy density 0, 3
J/cm2 to 3 J/cm2, preferably 0.
5 J/Cm" to 1.5 J/cm2. By setting the output of the excimer laser within the above range, it is preferable because it is possible to obtain a pie hole 20 with few irregularities such as protrusions, excellent surface quality, and a smooth processed wall. You can get results.

Furthermore, the processing frequency is not particularly limited, and may be approximately 1 to 200 Hz.

For processing, the excimer laser 18 may be irradiated continuously or intermittently. Note that the processing speed when irradiating the excimer laser 18 intermittently varies depending on the output of the excimer laser 18 and the thickness of the insulating layer such as the polyimide layer 16, but it is usually 0.2 to 0.5 μm/shot. be.

In addition, in order to prevent accidents such as disconnection of the second signal line that will be formed later, we have also developed a method for adjusting the imaging diameter of the excimer laser 18 by adjusting the position of the imaging lens (not shown) and the position of the processing target, and the energy density. 0.5~1, OJ/cm
It is preferable to taper the via hole 20 as shown in the illustrated example by a method of lowering it to 2.

Next, preferably, as shown in FIG. 4, the reaction product generated in the visor hole 20 is removed by repeatedly spraying a solution such as ethyl alcohol 22 into the visor hole 20 under pressure.

In the present invention, an insulating layer made of an insulating organic material, such as a polyimide layer 16, is processed using an excimer laser 18 to form pie holes 20, through holes, and the like. Therefore, after processing, reaction products such as carbon may be generated inside the wire hole 20 or around the processed hole, resulting in the surface of the wire hole 20 having an uneven shape. There is a risk of problems with heat resistance and insulation. Therefore, it is preferable to spray various solutions to remove this reaction product.

The solution to be applied may be appropriately determined depending on the insulating organic substance, and suitable examples include ethyl alcohol, pure water, and hexane. Moreover, the pressure at the time of spraying is usually about 0.1 atmosphere or less.

Next, as shown in FIG.
(see figure), the nickel layer 2 is used as the base layer.
6 is formed by sputtering, and a copper layer 28 is also formed by sputtering. The method for forming this underlayer is not limited to sputtering, but can be formed using various CVD (Che+++1cal vapor) methods.
rdeposition) P V D (Phy
Any known film forming method such as sic-al vapor deposition can be applied.

Further, a photoresist is coated on this underlayer by a known method such as a spin code, and exposed and developed by a method depending on the photoresist to be applied to form a photoresist layer 30.

Next, etching is performed using a method depending on the underlying layer to remove unnecessary underlying layers, and then the photoresist layer 30 is removed.
As shown in FIG. 6, copper is laminated on the remaining base layer by electroplating to increase the thickness of the copper layer 28, thereby completing the second signal line 32 and obtaining the multilayer wiring board 10 of the present invention.

Note that various known methods can be applied to the underlying layer at this time, regardless of whether it is dry etching or wet etching. Further, the method of laminating the copper layer 28 is not limited to electroplating, and various film forming methods such as sputtering can be applied.

Although the above-mentioned example was a case of forming a piere hole 20, the present invention is not limited to this, and may be applied when forming a through hole.

Further, the present invention is not limited to the above-mentioned examples, and it goes without saying that various changes and improvements may be made without departing from the gist of the present invention.

<Example> Hereinafter, the present invention will be explained in further detail by giving specific examples of the present invention.

[Example 1] Polyimide film processing experiment I Using an excimer laser using KrF” gas, a thickness of 1
An experiment was carried out in which holes were formed in a 25 μm polyimide film (manufactured by Toshi Corporation V).

First, machining frequency 10Hz, energy density E =
When a polyimide film was irradiated with 500 shots using an excimer laser of 1.5 J/cm', the diameter was 50 μm.
A machined hole of m was obtained. The inner wall of the processed hole was smooth, and no protrusions were observed.

Next, the energy density E is 3, 0, I7cm2
and 0 and 5 J/C [0' except that holes were formed in the polyimide film under the same conditions, and the energy density E = 0 and 5 J.
/CIO', it was possible to obtain a machined hole with a smooth inner wall without any protrusions, like the previous machined hole, but when the energy density was E = = 3, OJ/cm2, there were no protrusions on the inner wall. was observed, and it was not possible to obtain a smooth surface texture.

On the other hand, in each of the above experiments, the machining frequency was set to 10 to 10
An experiment was also conducted in which the frequency was changed to 0 Hz, and there was no change in the surface texture of the inner wall of the machined hole due to the change in frequency.

From the above results, in the above example, the energy density E of the excimer laser is 0.5.47 cm2 to 1,
It can be seen that about 5 J/cm' is preferable.

Na, 75, E=3. Machining speed in case of OJ/cm2 is 0
．． 45 μm/shot, and E=1.5.17 c
The processing speed in the case of m 2 was 0.3 μm/shot.

[Example 2 Copolyimide film processing experiment II A hole-opening processing experiment was conducted in the same manner as in Example 1, except that the polyimide film was changed to a 125 μm thick polyimide film (manufactured by Toshi Corporation H). .

In this case, the energy density E=0, 5
J/cm", it was possible to obtain a machined hole with inner wall properties applicable to via holes, but the energy density E
=1.5 and 3. In the case of OJ/cm2, some protrusions were observed on the inner wall of the machined hole, and there were some problems with accuracy etc. when applying it to a pie hole.

[Example 3] Manufacturing experiment of multilayer wiring board First, as shown in FIG. 1, on a 50 μm thick polyimide film (polyimide manufactured by Mitsui Toatsu ■)
A first signal line 14 made of copper was formed by photoetching. The thickness of the first signal line 14 was 10 μm, the width of one pattern was 30 μm, and the pattern pitch was 50 μm.

Next, a polyimide resin (manufactured by Hitachi Chemical, PIQ) dissolved in a mixed solution of N-methyl-2-pyrrolidone and dimethylacetamide was applied onto the first mesh line 14 and the polyimide film 12 using a spin cord. was dried and cured to form a polyimide layer 16 (second
(see figure). The thickness of the polyimide layer 16 after curing is 25μ
It was m.

As shown in FIG. 3, excimer laser 18 was irradiated onto a predetermined position of the polyimide layer 16 to form a piere hole 20. As shown in FIG. The excimer laser used was one that applied KrF gas, the processing frequency was 011z, and the energy density E was 1.5 J/cm2.
So, 160 shots were processed. In addition, by adjusting the imaging diameter of the laser beam by moving the position of the imaging lens (not shown), the via hole 20 can be adjusted from the outer diameter to 40°.
It was made into a tapered shape with an inner diameter of 25 to 30 μm.

On the inner wall of the pie hole 20 obtained in this way,
Since a reaction product mainly consisting of carbon was produced, this was removed by repeatedly spraying ethyl alcohol 22 under a pressure of 0.05 atmosphere or less as shown in FIG.

Then, as shown in FIG.
As a base layer for forming the substrate, nickel was first deposited to a thickness of 0.5 μm and copper was deposited to a thickness of 0.5 μm by sputtering. Furthermore, a photoresist (manufactured by Tokyo Ohka ■, OMR (negative type)) was applied using a spin code.
After exposure using a stepper, development was performed using a xylene solution to form a photoresist layer 30.

Next, after etching is performed to remove unnecessary underlying layers, the photoresist layer 30 is removed using a photoresist stripping solution (OM RIIJ Hina solution) as shown in FIG. A 10 μm electroplating process was performed to increase the thickness of the second signal line 32.

The obtained first signal line 14 and second signal line 32
were suitably connected by a piere hole 20.

<Effects of the Invention> As explained in detail above, according to the present invention, a strong alkali such as toxic hydrazine is used when manufacturing a multilayer wiring board in which an insulating organic material, particularly polyimide, is applied as an insulating layer. There is no need to perform wet etching, which is necessary and there is a risk of side etching, or dry etching, which is a complicated process that requires forming a mask with an inorganic layer or the like on the insulating layer and then etching the insulating layer. In addition, via holes, through holes, etc. can be quickly formed in the insulating layer.

Furthermore, the size of the via holes, through holes, and circuit patterns can be made smaller than in the past, and the precision can also be increased, so that a high-density, high-precision multilayer wiring board can be obtained.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5, and FIG. 6 are schematic cross-sectional views showing an example of the method for manufacturing a multilayer wiring board according to the present invention. Explanation of symbols 10... Multilayer wiring board, 12... Polyimide film, 14... First signal line, 16... Polyimide layer, 18... Excimer laser beam, 20... Pier hole, 22. ...Ethyl alcohol, 26...Nickel layer, 28...Copper layer, 30...Resist layer, 32...Second signal line FIG, 1

Claims (2)

[Claims] (1) A multilayer wiring board using an insulating organic material as an insulating layer, the multilayer wiring board having a connection hole for connecting a circuit pattern formed in the insulating layer using an excimer laser. (2) When manufacturing a multilayer wiring board using an insulating organic material as an insulating layer, a connecting hole is formed by irradiating a predetermined position of the insulating layer with an excimer laser, and a circuit pattern is connected through the connecting hole. A method for manufacturing a multilayer wiring board, characterized by: