JPH11150356A - Wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a wiring layer from being disconnected and a short circuit from occurring between the adjacent wiring layers by a method wherein a protective film is firmly deposited on the surfaces of the wiring layers. SOLUTION: A wiring layer 2 provided with a gold layer on its surface is formed on an insulating board 1 for the formation of a wiring board, wherein the surface of the wiring layer 2 is coated with a protective film 6 formed of SiO2- XNX (0.25<=X<=0.65). As the protective film 6 is formed of SiO2- XNX (0.25<=X<=0.65), Au-Si bonding is formed between the wiring layer 2 and the protective film 6 to firmly bond the layers 2 and 6 together. N is fixed to atomic or molecular-size lattice defect parts which are in the protective film 6 to serve as a path for H2 O to block up the path, so that molecules of H2 O hardly moves. Therefore, even if the wiring board is dipped into water, H2 O is restrained from penetrating into the protective film 6 so as not to expand it in volume, so that the surface of the wiring layer 2 is completely protected by the protective film 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wiring board having a wiring layer formed on the surface of an insulating substrate.

[0002]

2. Description of the Related Art Conventionally, a wiring board used for an electric circuit board or a package for housing a semiconductor element has a wiring layer of Mo.
-It is formed by employing a thick film forming technique such as the Mn method.

In the Mo-Mn method, an organic solvent and a solvent are added to a metal powder composed of a high melting point metal such as tungsten (W), molybdenum (Mo), and manganese (Mn).
A paste-shaped metal paste is applied to the outer surface of the raw or sintered ceramic body by printing in a predetermined pattern by a screen printing method, and then fired in a reducing atmosphere to sinter the high melting point metal and the ceramic body. It is a method of integrating.

In a wiring board having a wiring layer formed by the Mo-Mn method, a gold (Au) layer is applied to the surface of a wiring layer made of tungsten, molybdenum or the like to a predetermined thickness (several μm) by a plating method or the like. The corrosion resistance of tungsten and molybdenum is improved, and the electrical resistance of the wiring layer is reduced.

In recent years, it has been required to reduce the size of wiring boards and to form wiring layers with high density in response to the miniaturization of electronic equipment. Instead of forming a wiring layer by a thick film forming technique, a wiring board formed by a thin film forming technique capable of fine wiring has also been used.

A wiring board having this wiring layer formed by a thin film forming technique is provided on an insulating substrate by, for example, tantalum nitride (Ta _2).
N), an adhesion layer made of nickel-chromium alloy (NiCr) or the like, and a nickel-chrome alloy (NiCr) or titanium
An intermediate layer made of tungsten alloy (TiW), nickel (Ni), palladium (Pd) or the like, and a main conductor layer made of gold (Au) are formed into thin films by ion plating, sputtering, vapor deposition, plating, etc. Is formed, and then these layers are processed into a predetermined pattern by a photolithography technique to form a wiring layer.

In the wiring layer formed by the thin film forming technique, the adhesive layer functions to firmly adhere the wiring layer to the insulating base, and the intermediate layer suppresses the mutual diffusion between the adhesive layer and the main conductor layer. It functions to firmly adhere the main conductor layer to the adhesive layer.

In a wiring board in which such a wiring layer is formed by a thick film forming technique or a thin film forming technique, a protective film made of SiO _{2 is applied} to the upper surface of an insulating substrate including the surface of the wiring layer. The film prevents an external force from being applied to the wiring layer to cause a disconnection, and effectively prevents a conductor from adhering between adjacent wiring layers and causing a short circuit between the wiring layers.

The protective film made of SiO ₂ is applied to a predetermined thickness on the upper surface of the insulating substrate on which the wiring layer is formed by employing a sputtering method or the like.

[0010]

However, in this conventional wiring board, the adhesion strength between gold (Au) formed on the surface of the wiring layer and SiO ₂ forming the protective film is weak, For example, when H ₂ O is easily moved in SiO ₂ for forming a wiring board, when the wiring board is immersed in water for cleaning, the protective film made of SiO ₂ becomes H ₂ O.
There is a drawback that ₂ O moves to cause volume expansion of the protective film and the protective film is separated from the wiring layer.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and has as its object the purpose of firmly depositing a protective film on the surface of a wiring layer, and disconnecting the wiring layer by the protective film or providing an electrical connection between adjacent wiring layers. An object of the present invention is to provide a wiring board that can effectively prevent a short circuit from occurring.

[0012]

The present invention SUMMARY OF] is on an insulating substrate, a wiring substrate having a wiring layer having a gold layer on the surface, the surface of the wiring layer is _{SiO 2-X N X (0} . 25 ≦
X0.65).

Further, according to the present invention, the protective film has a thickness of 100
To 1000 nm.

According to the wiring substrate of the present invention, the protective film is made of Si.
Since it is formed of O _2−X N _x (0.25 ≦ X0.65), an Au—Si bond is formed between the wiring layer and the protective film, and the two are firmly joined. At the same time, N is fixed to the lattice defect portion of the atom and molecule size in the film, which becomes a path for H ₂ O to move in the protective film, and it becomes difficult for H ₂ O molecules to move in the film to block the path. Therefore, even if the wiring substrate is immersed in water, H ₂ O does not enter the protective film and the protective film does not undergo volume expansion, whereby the surface of the wiring layer can be completely protected by the protective film. .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a wiring board according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing one embodiment of a wiring board according to the present invention, wherein 1 is an insulating base, and 2 is a wiring layer.

The insulating substrate 1 functions as a support member for supporting the wiring layer 2, and is made of aluminum oxide sintered body, mullite sintered body, silicon carbide sintered body, aluminum nitride sintered body, glass ceramic sintered body. It is formed of an electrically insulating material such as a body.

When the insulating substrate 1 is made of, for example, an aluminum oxide sintered body, an appropriate organic solvent and a solvent are added to a raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide, and the mixture is mixed. A ceramic green sheet (ceramic green sheet) is formed by employing a doctor blade method, a calendar roll method, or the like, and then the ceramic green sheet is appropriately punched to form a predetermined shape. And at a high temperature (about 1600 ° C.).

On the upper surface of the insulating base 1, a plurality of wiring layers 2 are formed in a predetermined pattern by employing, for example, a thin film forming technique.

The wiring layer 2 formed by the thin film forming technique has a three-layer structure of an adhesive layer 3, an intermediate layer 4, and a main conductor layer 5, and the adhesive layer 3 is formed of the insulating base 1 and the wiring layer 2. The intermediate layer 4 functions to increase the adhesive strength, and the intermediate layer 4 is composed of the adhesive layer 3 and the main conductor layer 5.
The adhesion between the adhesive layer 3 and the main conductor layer 5 is improved.
And acts to prevent mutual diffusion.

The adhesive layer 3 of the wiring layer 2 is made of, for example, tantalum nitride (Ta ₂ N), nickel-chrome alloy (NiC
r), a material such as chromium (Cr), and is deposited on the insulating substrate 1 to a thickness of 20 nm to 500 nm by employing a thin film forming technique such as an evaporation method or an ion plating method.

When the thickness of the adhesive layer 3 is less than 20 nm, it is difficult to firmly adhere the wiring layer 2 to the insulating substrate 1. When the thickness exceeds 500 nm, the adhesive layer 3 is hardly adhered by a thin film forming technique. In addition, stress is generated in the adhesive layer 3 and is present inside the adhesive layer 3, and the intrinsic stress lowers the adhesive strength between the adhesive layer 3 and the insulating base 1.
Therefore, it is preferable that the thickness of the adhesive layer 3 be in the range of 20 nm to 500 nm.

On the upper surface of the adhesive layer 3, an intermediate layer 4 is formed by adhesion.
Chromium alloy (NiCr), titanium-tungsten alloy (TiW), nickel (Ni), palladium (Pd),
It is made of titanium (Ti) or the like, and is deposited to a thickness of 20 nm to 300 nm on the upper surface of the adhesive layer 3 by a thin film forming technique such as an evaporation method, an ion plating method, and a sputtering method.

When the thickness of the intermediate layer 4 is less than 20 nm, the adhesion between the adhesive layer 3 and the main conductor layer 5 is reduced and the mutual diffusion between the adhesive layer 3 and the main conductor layer 5 is effectively prevented. When the thickness exceeds 300 nm, the intermediate layer 4
When the is applied by the thin film forming technique, a stress is generated in the intermediate layer 4 and is present inside the intermediate layer 4, and the intrinsic stress reduces the adhesive strength between the adhesive layer 3 and the intermediate layer 4. Therefore,
The thickness of the intermediate layer 4 is preferably in the range of 20 nm to 300 nm.

Further, a main conductor layer 5 is formed on the upper surface of the intermediate layer 4 by vapor deposition, ion plating, sputtering, or the like.
The main conductor layer 5 is applied by a thin film forming technique such as a plating method, and mainly functions as a passage for conducting electricity.

The main conductor layer 5 is made of gold (Au) having a very low conduction resistance. If the thickness is less than 200 nm, the conduction resistance of the wiring layer 2 becomes high, which makes the wiring layer unsuitable for a wiring board. The thickness is preferably 200 nm or more, and 1000 nm to 10000 n in consideration of economy.
It is more preferable to set the range of m.

The wiring layer 2 formed on the insulating substrate 1 has the adhesive layer 3, the intermediate layer 4 and the main conductor layer 5 constituting the wiring layer 2 formed by employing a thin film forming technique. The wiring layer 2 can be miniaturized, and the wiring layer 2 can be formed on the small-sized insulating base 1 at a high density.

On the upper surface of the insulating base 1, a protective film 6 including the surface of the wiring layer 2 is applied. The protective film 6 causes the wiring layer 2 to be disconnected even when an external force is applied. No short circuit occurs between the wiring layers 2 even if a conductor adheres between the adjacent wiring layers 2.

The protective film 6 is made of SiO _2-x N _x (0.25
≦ X ≦ 0.65), and the SiO _2-x N _x (0.2
5 ≦ X ≦ 0.65) is a protective film 6 firmly bonded to the wiring layer 2 to form a Au over Si bonds between the gold constituting the main conductor layer 5 of the wiring layer 2, at the same time H ₂ O made There atoms in the film to be the path for moving the SiO ₂ film, N is fixed to a lattice defect portion of the molecular size, difficult to Makuchu to seal of H ₂ O movement path to move the H ₂ O molecules . Therefore, even if the wiring board is immersed in water, H ₂ O does not enter the protective film 6 and the protective film 6 does not expand in volume, thereby completely protecting the surface of the wiring layer 2 with the protective film 6. Becomes possible.

The SiO ₂ by the protective film 6 is sputtering in Ar atmosphere specifically containing N ₂
The target was placed, then both the shed Ar atoms excited by plasma SiO ₂ target to scatter the SiO ₂ by reacting _{N 2 SiO 2- X N X (} 0.25 ≦ X ≦
0.65) is formed on the insulating substrate 1 including the surface of the wiring layer 2 by depositing it on the upper surface of the insulating substrate 1. The X value of SiO _2-x N _x can be set to 0.25 to 0.65 by changing the N ₂ concentration in the Ar atmosphere.
Range.

[0030] In order the protective film 6 made of SiO _2-X N _X has the low concentration of N when the 0.25> X X value, a path that H ₂ O is moving in the protective film 6 Atomic and molecular size lattice defects in the film cannot be sufficiently closed by the fixation of N. As a result, when the wiring substrate is immersed in moisture, the protective film 6 expands in volume, and the protective film 6 becomes unwieldy. When X> 0.65, the internal stress of the protective film 6 increases, and the stress causes the protective film 6 to peel off.
Of the protective layer 6 on the wiring layer 2 is reduced, and the protective film 6 is easily peeled off from the wiring layer 2. Thus, the protective film 6 made of SiO _2-X N _X is X values 0.25 ≦ X
It is specified in the range of ≦ 0.65.

The protective film 6 has a thickness of 100 nm.
If it is less than 1, the electrical insulation of the protective film 6 decreases, making it difficult to electrically protect the wiring layer 2.
If the thickness exceeds 500 nm, the internal stress increases, and the stress reduces the adhesion strength of the protective film 6 to the wiring layer 2, and the protective film 6 is easily peeled from the wiring layer 2. Therefore, the protective film 6 has a thickness of 100 nm to 1000 nm.
It is preferable to set the range to nm.

Thus, according to the above-described wiring board, when electronic components such as semiconductor elements and capacitors are connected to the wiring layer 2 on the insulating substrate 1 via solder or the like, each electronic component is connected to the wiring layer 2.
Are electrically connected to each other.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. Although the description has been made with reference to a thin film forming technique having a three-layer structure of the adhesive layer 3, the intermediate layer 4, and the main conductor layer 5, it may be formed by a thick film forming technique having a gold layer on the surface. .

(Experimental Example) Next, the operation and effect of the present invention will be described based on the following experimental examples. First, a 100-nm-thick nickel-chromium layer and a 50-nm-thick layer were formed on an insulating substrate made of an aluminum oxide sintered body by sputtering.
A gold layer of 0 nm is sequentially deposited, and then a width of 200 μm and a length of 1000 μm are formed by photolithography.
To form a wiring layer.

Next, the entire upper surface of the insulating base on which the wiring layer is formed is formed to a thickness of 500 nm by sputtering.
In the protective film X value consists SiO _2-X N _X values shown in Table 1 were deposited, respectively Samples were prepared 500. next,
After each sample was immersed in water for 10 minutes, a tape was adhered to the protective film at an adhesion strength of 558 g / cm ² , and then the tape was pulled in the vertical direction to count the number of the peeled protective film and calculate the peeling rate. .

Table 1 shows the results.

[0037]

[Table 1]

As is clear from Table 1, SiO _2-x N _x
When the X value of the protective film made of 0.25 ≦ X ≦ 0.65, the peeling rate of the protective film becomes 40% or less. In particular, when the X value is 0.30 ≦ X ≦ 0.50, the peeling of the protective film occurs. Rate 8
% Or less.

[0039]

According to the wiring board of the present invention, the protective film is made of S
Since it is formed of iO _2-x N _x (0.25 ≦ X0.65), an Au—Si bond is formed between the wiring layer and the protective film, and the two are firmly joined. At the same time, N is fixed to the lattice defect portion of the atom and molecule size in the film, which becomes a path for H ₂ O to move in the protective film, and it becomes difficult for H ₂ O molecules to move in the film to block the path. Therefore, even if the wiring substrate is immersed in water, H ₂ O does not enter the protective film and the protective film does not undergo volume expansion, whereby the surface of the wiring layer can be completely protected by the protective film. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a wiring board of the present invention.

[Explanation of symbols]

 1 ··· Insulating substrate 2 ··· Wiring layer 6 ··· Protective film

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 26, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

[0012]

The present invention SUMMARY OF] is on an insulating substrate, a wiring substrate having a wiring layer having a gold layer on the surface, the surface of the wiring layer is _{SiO 2-X N X (0} . 25 ≦
X ≦ 0.65).

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

According to the wiring substrate of the present invention, the protective film is made of Si.
Since it is formed of O _2−X N _x (0.25 ≦ X ≦ 0.65), an Au—Si bond is formed between the wiring layer and the protective film, and both are firmly joined. At the same time, N is fixed to the lattice defect portion of the atom and molecule size in the film, which becomes a path for H ₂ O to move in the protective film, and it becomes difficult for H ₂ O molecules to move in the film to block the path. Therefore, even if the wiring substrate is immersed in water, H ₂ O does not enter the protective film and the protective film does not undergo volume expansion, whereby the surface of the wiring layer can be completely protected by the protective film. .

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction contents]

[0039]

According to the wiring board of the present invention, the protective film is made of S
Since it is formed of iO _2-x N _x (0.25 ≦ X ≦ 0.65), an Au—Si bond is formed between the wiring layer and the protective film, and the two are firmly joined. At the same time, N is fixed to the lattice defect portion of the atom and molecule size in the film, which becomes a path for H ₂ O to move in the protective film, and it becomes difficult for H ₂ O molecules to move in the film to block the path. Therefore, even if the wiring substrate is immersed in water, H ₂ O does not enter the protective film and the protective film does not undergo volume expansion, whereby the surface of the wiring layer can be completely protected by the protective film. .

Claims (2)

[Claims] 1. A wiring board having a wiring layer having a gold layer formed on a surface thereof on an insulating substrate, wherein the surface of the wiring layer is made of Si.
O _2-X N _X wiring board, characterized in that it is coated with a protective layer made of (0.25 ≦ X0.65). 2. The protective film has a thickness of 100 to 1000 n.
2. The wiring board according to claim 1, wherein m is m.