JPH08203907A - External connection bump electrode and forming method thereof - Google Patents

Abstract

PURPOSE: To enable an underlying connecting layer of a bump electrode to be formed on an Al electrode by a simple manufacturing steps at low cost by a method wherein an alumina film having multiple pores in provided on the connecting part with an external electrode of a wiring layer so as to bury excellent conductors in the pores for providing the underlying connecting layer on the conductors. CONSTITUTION: An alumina film 6 having multiple pores is provided on the connecting part with an external electrode of a wiring layer 2 provided on a substrate 1 so as to bury excellent conductors 8 in the pores. Furthermore, an underlying connecting layer 10 is provided on the excellent conductors 8 and then a bump electrodes forming connecting layer 11 is provided on the underlying connecting layer 10 so as to form the bump electrode. For example, the alumina film 6 having multiple pores is formed by anode-oxidizing a part of the wiring layer 2 mainly comprising aluminum. Next, after the electrolytic deposition of the excellent conductors 8 in the pores, the underlying connecting layer 10 to be the underlying layer of the bump electrode forming connecting layer 11 is formed on the excellent conductors 8 by non-electrolytic plating process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protruding electrode for external connection and a method for forming the same, and more particularly to a bump electrode provided in a semiconductor device which can be directly mounted on a mounting substrate or a mounting substrate for mounting the semiconductor device. The present invention relates to a protruding electrode for external connection such as a pad electrode provided and a method for forming the same.

[0002]

2. Description of the Related Art In recent years, as the number of terminals of a semiconductor device has increased, a TAB for mounting the semiconductor device without using wire wiring.
A method, or a method of directly flip-chip bonding a semiconductor device, etc. is rapidly developing, and in order to cope with such a bonding method, an aluminum wiring layer provided in the semiconductor device is connected to an external terminal for connection. Bump electrodes are provided, or pad electrodes are provided on the side of a mounting substrate on which a semiconductor device is mounted.

In the conventional process of forming bump electrodes for external connection such as bump electrodes, Al is formed on the aluminum wiring layer.
Although a barrier metal such as a Ti film or a Ni film is provided to prevent mutual diffusion between the Pb-Sn solder layer or the Au layer serving as a bump electrode, the barrier metal such as the Ti film or the Ni film is electrolessly electrolyzed. Since it could not be directly formed by the plating method, the step shown in FIG. 7 was usually taken as a method for forming the bump electrode.

FIG. 7 shows a schematic manufacturing process of a conventional bump electrode, which is composed of eight integrated processes, and the process surrounded by a line in the drawing is a process capable of a series of continuous processing. Is shown.

First, as a first step, a Ti film and a Ni film to be a barrier metal are sequentially deposited on an aluminum wiring layer formed on a semiconductor substrate by a vapor deposition method or a sputtering method. Next, as a second step, a resist layer corresponding to the bump electrode forming pattern is provided by applying and patterning a resist layer, and then as a third step, the Ni film is etched so as to leave the bump electrode forming pattern, and then, After removing the resist layer as a fourth step, a plating resist layer is newly formed by coating and patterning a plating resist layer as a fifth step.

Next, as a sixth step, a Ni plating layer or a Cu plating layer serving as a barrier metal is formed on the exposed portion of the Ni film by the electroplating method using the plating resist layer as a mask, and then bump electrodes are formed by the electroplating method. The Au plating layer or the Pn-Sn plating layer is formed thickly. Next, after removing the plating resist layer as a seventh step, an Au plating layer or Pn-S is formed as an eighth step.
The exposed portion of the Ti film is etched using the n-plated layer as a mask to complete the bump electrode.

In addition to the formation method shown in FIG. 7, an electroless Ni plating layer may be directly formed on the aluminum wiring layer by using a zincate method in which Zn (zinc) is substituted and deposited on the aluminum wiring layer. Is being considered.

[0008]

However, in the conventional manufacturing method shown in FIG. 7, there is a problem that the cost is considerably high because the process is complicated and it takes time.
Further, in the zincate method capable of direct electroless Ni plating, the pH of the zincate processing solution is as high as about 13, so that the resist as a plating mask cannot withstand the zincate processing solution, and this method The electroless Ni-plated layer has a problem that peeling is likely to occur because the adhesion to the base is weak.

Therefore, according to the present invention, a base conductive layer including an electroless plating layer serving as a base layer for a bump electrode layer or a pad electrode layer or the like for a protruding electrode is formed on an aluminum electrode by a simple manufacturing process at a low cost. With the goal.

[0010]

According to the present invention, in a protruding electrode for external connection, a large number of pores are formed in a connection portion of a wiring layer (2 in FIG. 3) provided on a substrate (1 in FIG. 3) with the external electrode. An alumina film (6 in FIG. 3) having (7 in FIG. 3) is provided, and a good conductor (8 in FIG. 3) embedded in the pores,
The protruding electrode is formed by the underlying conductive layer (10 in FIG. 3) provided on the good conductor and the conductive layer for forming a protruding electrode (11 in FIG. 4) provided on the underlying conductive layer. To do.

Further, according to the present invention, in the external connection protruding electrode, the substrate is a semiconductor substrate (1 in FIG. 3), and the wiring layer provided on the substrate is a wiring layer containing aluminum as a main component (see FIG. 3). 2) of No. 2), and the alumina film also penetrates into a part of this wiring layer. In the present specification, “a wiring layer containing aluminum as a main component” means a pure aluminum wiring layer and 1% or less of Si.
It means an aluminum alloy wiring layer whose main component is aluminum containing Cu, Cu, or the like.

Further, according to the present invention, in the external connection projecting electrode, an oxidation preventing conductive layer (see FIG. 5) is provided between the base conductive layer (10 in FIG. 5) and the projecting electrode forming conductive layer (13 in FIG. 5). Of 1
2) is interposed. Also, the present invention
In the external connection protruding electrode, the substrate is a mounting substrate (14 in FIG. 6), the wiring layer provided on the substrate is a wiring layer made of Cu (15 in FIG. 6), and the alumina film (FIG. 6) is used.
18) and the Cu wiring layer are characterized by interposing an aluminum layer (16 in FIG. 6) which is not aluminized.

Further, according to the present invention, in the protruding electrode for external connection, the thickness of the good conductor embedded in the pore is not less than ½ of the depth of the pore and not more than the depth of the pore. It is characterized by being made thick.

Further, according to the present invention, in the protruding electrode for external connection, an electroless Ni plating layer, an electroless C layer is used as a base conductive layer.
u plating layer, electroless Pd plating layer, electroless Pd-Sn-
It is characterized in that at least one of the Pb plating layers is used and the thickness thereof is set to 0.5 μm to 5 μm.

Further, according to the present invention, in the method for forming a protruding electrode for external connection, the wiring layer (2 in FIG. 3) provided on the substrate (1 in FIG. 3) at least covers the connection portion with the external electrode. Conductive layer composed mainly of aluminum (4 in FIG. 2)
Is deposited, and at least a part of this conductive layer is anodized to form an alumina film (6 in FIG. 3) having a large number of pores (7 in FIG. 3). Then, a good conductor ( After electrolytically depositing 8) in FIG. 3, a base conductive layer (10 in FIG. 4) which becomes a base layer of the conductive layer for forming bump electrodes (11 in FIG. 4) is formed on the good conductor by electroless plating. It is characterized in that at least a part thereof is formed.

According to the present invention, in the method of forming a protruding electrode for external connection, the substrate is a semiconductor substrate, and the wiring layer provided on the substrate is a wiring layer containing aluminum as a main component. And a conductive layer containing aluminum as a main component, which is converted to an alumina film having a thickness of 200 Å or more and ⅔ or less of the total thickness of the wiring layer and the conductive layer.

Further, according to the present invention, in the method of forming a protruding electrode for external connection, an oxidation preventing conductive layer (12 in FIG. 5) is provided between the underlying conductive layer (10 in FIG. 5) and the protruding electrode forming conductive layer.
And a conductive layer for forming a bump electrode is formed by transferring a solder ball (13 in FIG. 5).

Further, in the present invention, in the method of forming a protruding electrode for external connection, the substrate is a mounting substrate (14 in FIG. 6), and the wiring layer provided on the substrate is a wiring layer made of Cu (see FIG. 6). 15), and a conductive layer containing aluminum as a main component (16 in FIG. 6) is deposited to 3000 Å or more so as to cover at least the connection portion of the wiring layer with the external electrode. , Over 200Å,
Further, it is characterized in that 2/3 or less of the total thickness of the conductive layer is converted into an alumina film (18 in FIG. 6).

Further, according to the present invention, in the method of forming a protruding electrode for external connection, Ni-P is used when the underlying conductive layer is formed.
At least one of the plating method and the Ni-B plating method is used.

[0020]

In the present invention, an alumina film having small pores is provided in the connection portion of the wiring layer provided on the substrate with the external electrode, and a good conductor is embedded in the pores.
A barrier that can maintain good electrical continuity with the aluminum-based layer remaining under the alumina film, and that direct electroless plating on the aluminum layer was virtually impossible. The underlying conductive layer functioning as a metal can be formed by electroless plating.

Further, by using the semiconductor substrate as the substrate and the wiring layer containing aluminum as the main component as the wiring layer, the bump electrodes for the semiconductor device are formed. In this case, alumina is used. It is possible to thin the conductive layer containing aluminum as a main component, which is converted into a film. Further, by providing the conductive layer for preventing oxidation on the surface of the underlying conductive layer, it becomes possible to form the conductive layer for forming the protruding electrode by a method other than the electrolytic plating method or the vapor deposition method.

A mounting board is used as the board, and
Even when a wiring layer made of Cu is used as the wiring layer, a thick conductive layer is provided between the alumina film and the Cu wiring layer to such an extent that a conductive layer containing aluminum which is not aluminized as a main component remains. The film can be stably formed.

Further, the thickness of the good conductor to be embedded in the pores is set to be 1/2 or more of the depth of the pores and less than or equal to the depth of the pores. The underlying conductive layer can be formed with good adhesion.

At least one of an electroless Ni plating layer, an electroless Cu plating layer, an electroless Pd plating layer, and an electroless Pd-Sn-Pb plating layer is used as the underlying conductive layer, and the thickness thereof is used. Is 0.5 μm to 5 μm, Sn can be prevented from diffusing in the Pb-Sn solder plating layer as the conductive layer for forming the protruding electrode, and the internal stress of the underlying conductive layer can be reduced to reduce the protrusion. It becomes possible to prevent peeling of the electrodes.

Further, a conductive layer containing aluminum as a main component is deposited so as to cover at least the connection portion of the wiring layer provided on the substrate with the external electrode, and the conductive layer of the connection portion with the external electrode is anodized. To form an alumina film having a large number of pores, and then electrolytically depositing a good conductor in the pores, and at least the underlying conductive layer to be the underlying layer of the conductive layer for forming bump electrodes by electroless plating. By forming a part, the main part of the step of forming the external connection protruding electrode can be performed in a series of continuous steps, and therefore, the manufacturing process can be simplified.

When a semiconductor substrate is used as the substrate and a wiring layer containing aluminum as the main component is used as the wiring layer, the wiring layer and the conductive layer containing aluminum as the main component are 200 Å or more, and By converting ⅔ or less of the total thickness of this wiring layer and this conductive layer into an alumina film, a good conductor can be embedded in the pores formed in the alumina film with good reproducibility.

Further, by interposing an oxidation preventing conductive layer between the underlying conductive layer and the protruding electrode forming conductive layer, and forming the protruding electrode forming conductive layer by transferring a solder ball, the protruding electrode forming conductive layer is formed. The formation process of the conductive layer can be diversified.

A mounting board is used as the board, and
Even when a wiring layer made of Cu is used as the wiring layer, a conductive layer containing aluminum as a main component is deposited in an amount of 3000 Å or more so as to cover at least the connection portion of the wiring layer with the external electrode. It becomes possible to convert the conductive layer having a thickness of 200 Å or more and ⅔ or less of the total thickness of the conductive layer into an alumina film, and therefore, a good conductivity is provided in the pores formed in the alumina film. The body can be embedded with good reproducibility.

When forming the underlying conductive layer, Ni-
By using at least one of the P plating method and the Ni—B plating method, the underlying conductive layer can be formed on the good conductor by electroless plating with good reproducibility.

[0030]

【Example】

FIG. 1 is an explanatory view of a schematic manufacturing process of a bump electrode of the present invention. The present invention is a first step of forming an aluminum layer on a silicon semiconductor substrate, and a second step of applying and patterning a resist layer. , Aluminum layer anodizing process-
Step of depositing good conductor-Electroless plating step-Electrolytic Au (P
b-Sn) A series of continuous third step of plating step, a fourth step of removing the resist layer, and a fifth step of etching the aluminum layer.

As described above, the manufacturing process of the present invention is composed of five integrated processes, which is simpler than the conventional manufacturing process which requires eight integrated processes. Accordingly, the manufacturing time can be shortened.

Next, with reference to FIGS. 2 to 4, a specific manufacturing process of the first embodiment of the present invention will be described along with the schematic manufacturing process shown in FIG. 2B to FIG.
FIG. 2D is an enlarged view of the opening in the circle of the broken line in FIG.

Referring to FIG. 2A, the final aluminum wiring layer 2 having a thickness of 8000 Å provided on the silicon semiconductor substrate 1 via an interlayer insulating film (not shown) is covered with a cover film 3 made of a PSG film. do it,
After forming an opening having a diameter d ₁ of 100 μm in the cover film, 10 is provided for establishing electrical continuity with the final aluminum wiring layer 2 and enabling application of an electric field during electrolytic plating.
An aluminum layer 4 having a thickness of 00Å is vapor-deposited on the entire surface, then a resist layer 5 having a thickness of 5 μm is applied, and then an opening corresponding to the opening of the cover film 4 is formed.

The cover film 3 is not limited to the PSG film, and other insulating films used as an interlayer insulating film such as a BPSG film may be used, and the aluminum layer 4 is pure aluminum. It does not have to be present, and an aluminum alloy containing aluminum as a main component containing 1% or less of Si or Cu may be used, and the thickness thereof is 30.
It may be in the range of 0 to 8000Å.

Next, referring to FIG. 2B, the semiconductor substrate 1 on which the resist layer is formed is subjected to
An alumina coating 6 having a thickness of 3000 Å is formed by immersing in a treatment solution based on a sulfuric acid bath consisting of 1% sulfuric acid and aluminum and anodizing by passing a current having a current density of 1 A / dm ² for 60 seconds. This alumina film 6 has a diameter d
₂ is 150-200 Å and the hole called pore 7 is 1 cm ²
Billions are formed per billion.

The alumina coating 6 has a thickness of 200 Å or more and the total aluminum layer thickness (in this case, 800
2/3 or less of 0 Å + 1000 Å = 9000 Å), and when the thickness of the alumina coating 6 is 200 Å or less, pore 7
If a good conductor does not enter, and if it is too thick, the total aluminum layer becomes too thin and the resistance of the wiring layer increases too much. The conditions of this anodizing treatment are not limited to the above numerical values, preferably the current density is 0.1 to 5.0 A / dm ² , and the time is 5 to 600 seconds. Is an oxalic acid bath (oxalic acid 2
˜5 wt%, aluminum 3 to 20 g / l).

Then, as shown in FIG. 3 (c), Fe (iron) having a thickness of 2500 Å is used as a good electric conductor in the pores 7 by an electrolytic plating method in which an electric field of 12 V is applied for 40 seconds using a ferrous sulfate solution. To form a good conductor burying layer 8. In this case, the alumina coating 6
Since the film thickness of the alumina in the portion 9 in contact with the final aluminum wiring layer 2 is extremely thin, no problem occurs in electrolytic plating.

The good conductor embedding layer 8 is not limited to Fe, but may be any metal that can be subjected to electrolytic plating, and in terms of electrical conductivity and cost, for example, N may be used.
i or Cu may be used, but it is desirable that the material is of the same family as the electroless plating layer provided thereon.

The thickness is 2500 Å with respect to the pore 7 having a depth of 3000 Å for the purpose of forming irregularities on the surface in order to strengthen the adhesion with the electroless plating layer provided in the subsequent step. However, the thickness is not limited to such a thickness, and it is sufficient if the thickness is 1/2 or more of the depth of the pore 7 and less than or equal to the depth of the pore 7. Is less than 1/2, it becomes difficult to form the electroless plating layer in the subsequent step.

See FIG. 3 (d). Next, N using sodium diphosphate as a reducing agent is used.
An iP electroless plating is performed to form an electroless Ni plating layer 10 having a thickness of 2 μm and containing 15% or less of P. The electroless Ni plating layer 10 is provided as a barrier metal for preventing Sn in the Pb-Sn solder forming the bump electrode from diffusing to the aluminum wiring layer side, and its thickness is 0.5 μm or more is required to function as a barrier metal.
In order not to increase the internal stress so much, the thickness is preferably 5 μm or less.

Next, referring to FIG. 4 (e), a Pb-Sn plated layer 11 of 50 μm is formed on the electroless Ni plated layer 10 by the conventional electrolytic plating method. The thickness of the Pb-Sn plated layer 11 is 50 μm.
The number is not limited to m, and may be appropriately determined according to the size of the required semiconductor device, but normally 2
The range of 0 to 70 μm is used.

Next, after removing the resist layer, the exposed aluminum layer is removed by etching using phosphoric acid to remove Pb-Sn.
The surface of the plated layer 11 is covered with an anti-oxidant flux, and then wet-back is performed at a temperature equal to or higher than the melting point of the Pb-Sn plated layer 11 to round the Pb-Sn plated layer 11.
Complete the bump electrodes.

Although the electroless Ni plating layer is formed by Ni-P system plating in the above-mentioned embodiment, it may be formed by Ni-B system plating using sodium borohydride or potassium borohydride as a reducing agent. Well, in the case of this Ni-B system plating, 1 to 3% of B is contained in the electroless Ni plating layer.
(Boron) will be contained.

This Ni-B system plating is superior to the Ni-P system plating in the initial reaction and the reaction is stabilized, but since the film forming rate is slow, a thin Ni-
It is also possible to form a B-based plating layer and then increase the thickness of the plating layer by Ni-P-based plating.

Further, since the electroless plating layer has a low film forming rate, first, a thin electroless Ni plating layer of about 0.1 μm is formed to the extent that electrolytic plating can be performed in the subsequent step, and then the barrier metal layer is formed. The shortage of the film thickness may be compensated by an electrolytic Ni plating layer or an electrolytic Cu plating layer having a small internal stress and a high film formation rate.

Although the electroless Ni plating layer is used as the electroless plating layer in the above embodiment, the electroless plating layer is not limited to Ni, and Pb- which forms the bump electrode causing deterioration of the aluminum wiring layer. Sn in Sn solder
May be any conductor having a barrier function for preventing the diffusion of aluminum to the aluminum wiring layer side, such as Cu, Pd,
Alternatively, a Pd-Sn-Pb alloy or the like may be used. Further, when an electroless Cu plating layer is used, a thin electroless Cu plating layer is formed, and then the insufficient film thickness is removed by an electrolytic Ni plating layer or electrolytic Cu plating. You may supplement with layers. Note that Pd
Although Sn is also contained in the -Sn-Pb alloy, Pd-
Due to the high melting point of the Sn-Pb alloy, the diffusion of Sn in the Pd-Sn-Pb alloy is less of a problem.

Further, in the step of etching the aluminum layer 4, hydrofluoric acid having a concentration of 1 to 10% may be used instead of phosphoric acid. Further, when the bump electrodes are formed, Pb- formed by electrolytic plating is used. Although the Sn plating layer 11 is used, the Sn plating layer 11 is not limited to such an electrolytic Pb-Sn plating layer. For example, an electrolytic Au plating layer formed by an electrolytic plating method or an Au layer formed by a vapor deposition method or a sputtering method. Alternatively, a Pb-Sn layer may be used.

Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, oxidation for preventing oxidation of the surface of the electroless Ni plating layer is performed between the electroless Ni plating layer forming step and the bump electrode forming conductive layer forming step in the first embodiment. The conductive layer for prevention is provided, and the manufacturing process thereof is exactly the same as that of the first embodiment up to the electroless Ni plating layer forming process of FIG. 3D, so the subsequent processes will be described. .

See FIG. 5A. Following formation of the electroless Ni plating layer 10, 400 Å
The electroless Au plating layer 12 is formed to prevent the surface of the electroless Ni plating layer 10 from being oxidized. In addition, this electroless Au
The thickness of the plating layer is 30 in order to function as an antioxidant.
A thickness of 0Å or more is good.

Next, after removing the resist layer, the exposed aluminum layer is removed by etching using the electroless Au plating layer 12 as a mask, and then the previously formed Pb-S is formed.
The n solder balls 13 are transferred to form bump electrodes.

The transfer of the solder balls is performed by forming Pb-Sn solder balls at positions corresponding to the bump electrode forming positions of the silicon semiconductor substrate 1 on the solder ball forming substrate, and then forming the solder ball forming substrate and the silicon semiconductor. The solder ball is transferred to a predetermined position by aligning it with the substrate 1 in a face down bonding manner, and the solder ball is rounded by wet back.

Also in the second embodiment, as in the first embodiment, a Cu layer and Pd formed by an electroless plating method are used instead of the electroless Ni plating layer as the underlayer.
A layer, a Pd-Sn-Pb alloy layer, or the like may be used. Furthermore, even when an electroless Ni plating layer or an electroless Cu plating layer is used, a thin electroless Ni plating layer or an electroless Cu plating layer is used. After the formation, the shortage of the film thickness may be compensated by the electrolytic Ni plating layer or the electrolytic Cu plating layer.

In the second embodiment, the electroless Au plating layer 12 is used for preventing oxidation, but the electroless Au plating layer is not limited to the electroless Au plating layer 12 and the like. Any material that is harder to oxidize than the formation may be used, such as Au, Ag, Sn, Pb-Sn, or Pd-S.
It suffices to select and use n-Pb or the like according to the material of the underlying layer, and as a film forming method thereof, either an electroless plating method or an electrolytic plating method may be used.

In the second embodiment, the bump electrodes are formed by transferring Pb-Sn solder balls, but in this case, electroless Au is formed on the surface of the underlayer such as the electroless Ni plating layer. Since an anti-oxidation conductive layer such as a plating layer is provided, there is an advantage that various bump electrode forming methods can be used. For example, a screen printing method or a conductive resin may be used. .

When a conductive resin is used, a resin having thermosetting resin such as an epoxy resin as a base material is mixed with conductive particles such as Au of resin particles or metal particles. Then, a conductive resin layer is formed by punching the conductive resin layer into a predetermined pattern to form bump electrodes.

Further, in the first and second embodiments, the aluminum layer 4 is formed on the entire surface. However, a dedicated wiring layer for electrical conduction is provided in advance, and this wiring layer An aluminum layer may be partially formed so as to be electrically connected. In this case, this dedicated wiring layer is drawn out to the outer peripheral portion of the semiconductor device,
When the wafer is divided into individual semiconductor chips, the wiring layer drawn out to the outer peripheral portion may be cut at the same time to make each bump electrode an independent electrode.

Further, in the above first and second embodiments, the description has been made by using the silicon semiconductor device, but the present invention is not limited to the silicon semiconductor device, and a compound semiconductor device using GaAs or the like can be used. Is also effective.

Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment relates to a structure and a forming method of a pad electrode of a mounting board made of ceramics or the like for mounting a semiconductor device, and its manufacturing process is basically the same as that of the first embodiment.

See FIG. 6A. On the ceramic substrate 14 provided with the Cu wiring layer 15, 5
An aluminum layer 16 having a thickness of 000Å is vapor-deposited on the entire surface,
Next, after forming a resist layer 17 having an opening corresponding to the pad electrode forming portion, the alumina film 1 having a large number of pores 19 is formed by the same process as in the first embodiment.
8, Fe good conductor embedding layer 20, electroless N as a base layer
The i-plated layer 21 is formed.

Next, after removing the resist layer, the unnecessary aluminum layer 16 exposed by using the electroless Ni plating layer 21 as a mask is removed by etching, and then the electroless Pb-Sn is removed.
By the plating method, P only on the electroless Ni plating layer 21
A pad electrode is formed by plating the b-Sn solder layer 22.

In this case, the solder dipping method may be used instead of the electroless Pb-Sn plating method. Further, instead of such an electroless Pb-Sn plating method or a solder dipping method, an electroless Ni plating layer 21 as a base layer is formed in the same manner as in the first embodiment, and then Pb is applied by an electrolytic plating method. -The Sn plating layer may be formed, and then the resist layer and the unnecessary aluminum layer may be removed to complete the pad electrode.

Further, in the third embodiment, since the wiring layer is Cu, it is necessary to form the alumina film 5
Although an aluminum layer having a thickness of 000 Å is formed, a thickness of 3000 Å or more is sufficient as long as an alumina film having the same thickness as in the first embodiment can be formed.

Further, the material of the mounting substrate is not limited to ceramics, but may be another insulating substrate such as a resin substrate, and the wiring layer is not limited to the Cu wiring layer. As a method for forming the aluminum layer, a sputtering method may be used instead of the vapor deposition method.

Also in the third embodiment, the material and forming method of the good conductor embedding layer, the underlayer, and the conductive layer for forming the pad electrode are the same as those described in the embodiment. The present invention is not limited to this, and various modes are possible just as in the first embodiment.

That is, the good conductor embedding layer is not limited to Fe, and may be any metal that can be subjected to electrolytic plating treatment, for example, Ni or Cu, or the formation of an electroless Ni plating layer. As the method, in addition to the Ni-P electroless plating method using sodium diphosphate as a reducing agent, a Ni-B plating method using sodium borohydride or potassium borohydride as a reducing agent may be used. In addition, first, a thin Ni-B system plating layer is formed,
Then, the thickness of the plating layer may be increased by Ni-P system plating.

As the underlayer, Cu, Pd formed by an electroless plating method other than the electroless Ni plating layer,
Alternatively, a Pd-Sn-Pb alloy or the like may be used, and when an electroless Ni plating layer or an electroless Cu plating layer is used, a thin electroless Ni plating layer or electroless C layer is used.
After forming the u-plated layer, the insufficient thickness may be supplemented with an electrolytic Ni-plated layer or an electrolytic Cu-plated layer.

In the step of etching the aluminum layer, phosphoric acid or hydrofluoric acid having a concentration of 1 to 10% may be used. Further, when forming the pad electrode, electrolytic Pb-Sn is used.
Although the plated layer is used, the plated layer is not limited to such a Pb-Sn plated layer, and an Au layer or a Pb-Sn layer formed by a vapor deposition method or a sputtering method may be used.

[0068]

According to the present invention, the bump electrodes of the semiconductor device or the bump electrodes for external connection such as the pad electrodes of the mounting substrate can be processed in a series of continuous manufacturing steps, so that the manufacturing steps are simplified. Thus, it is possible to provide a semiconductor device or a mounting substrate for a semiconductor device which has stable characteristics at low cost.

[Brief description of drawings]

FIG. 1 is an explanatory view of a schematic manufacturing process of a bump electrode of the present invention.

FIG. 2 is an explanatory view of a manufacturing process up to the middle of the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a manufacturing process up to the middle of FIG. 2 and subsequent steps of the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of the manufacturing process after the process of FIG. 3 of the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a manufacturing process according to the second embodiment of the present invention.

FIG. 6 is an explanatory diagram of a manufacturing process according to the third embodiment of the present invention.

FIG. 7 is an explanatory diagram of a schematic manufacturing process of a conventional bump electrode.

[Explanation of symbols]

 1 Silicon Semiconductor Substrate 2 Final Aluminum Wiring Layer 3 Cover Film 4 Aluminum Layer 5 Resist Layer 6 Alumina Film 7 Pore 8 Good Conductor Embedding Layer 9 Bottom of Alumina Film 10 Electroless Ni Plating Layer 11 Pb-Sn Solder Plating Layer 12 No Electrolytic Au plating layer 13 Pb-Sn solder ball 14 Ceramics substrate 15 Cu wiring layer 16 Aluminum layer 17 Resist layer 18 Alumina film 19 Pore 20 Good conductor embedding layer 21 Electroless Ni plating layer 22 Pb-Sn solder layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Yoda 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Kenichi Nagashige 1015, Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (11)

[Claims] 1. An alumina film having a large number of pores provided in a connection portion of a wiring layer provided on a substrate with an external electrode, a good conductor embedded in the pores, and a base conductivity provided on the good conductor. A protrusion electrode for external connection, comprising a layer and a protrusion electrode-forming conductive layer provided on the underlying conductive layer. 2. The substrate is a semiconductor substrate, and the wiring layer is a wiring layer containing aluminum as a main component,
The protruding electrode for external connection according to claim 1, wherein the alumina film also penetrates into a part of the wiring layer. 3. The protruding electrode for external connection according to claim 1, wherein an oxidation conductive layer is interposed between the underlying conductive layer and the protruding electrode forming conductive layer. 4. The conductive layer containing aluminum as a main component, which is not aluminized between the alumina film and the Cu wiring layer, wherein the substrate is a mounting substrate, the wiring layer is a wiring layer made of Cu. The protruding electrode for external connection according to claim 1, wherein: 5. The thickness of the good conductor to be embedded in the pores is set to a thickness not less than ½ of the depth of the pores and not more than the depth of the pores. The protruding electrode for external connection according to any one of claims 1 to 4. 6. At least one of an electroless Ni plating layer, an electroless Cu plating layer, an electroless Pd plating layer, and an electroless Pd—Sn—Pb plating layer is used as the underlying conductive layer, and The thickness of the underlying conductive layer is 0.5 μm to 5 μm
The protruding electrode for external connection according to any one of claims 1 to 5, wherein 7. A conductive layer containing aluminum as a main component is deposited so as to cover at least a connection portion of a wiring layer provided on a substrate with an external electrode, and then at least a part of the conductive layer is anodized. To form an alumina film having a large number of pores, and then electrolytically deposit a good conductor in the pores, followed by electroless plating to form an underlying layer of a conductive layer for forming a protruding electrode on the good conductor. A method of forming a protruding electrode for external connection, characterized in that at least a part of a base conductive layer to be formed is formed. 8. The substrate is a semiconductor substrate, and the wiring layer is a wiring layer containing aluminum as a main component,
It is characterized in that the wiring layer and the conductive layer containing aluminum as a main component are converted to the alumina coating in a thickness of 200 Å or more and 2/3 or less of the total thickness of the wiring layer and the conductive layer. The method for forming a protruding electrode for external connection according to claim 7. 9. The conductive layer for preventing oxidation is formed on the surface of the underlying conductive layer, and the conductive layer for forming the bump electrode is formed by transferring a solder ball. Of forming a protruding electrode for external connection of. 10. The substrate is a mounting substrate, the wiring layer is a wiring layer made of Cu, and the conductive layer containing aluminum as a main component is deposited in an amount of 3000 Å or more to contain aluminum as a main component. The conductive layer is 200
The method for forming a protruding electrode for external connection according to claim 7, wherein Å or more and ⅔ or less of the total thickness of the conductive layer is converted into the alumina film. 11. When forming the underlying conductive layer, Ni is used.
11. At least one of a -P plating method and a Ni-B plating method is used, and any one of claims 7 to 10 is characterized.
Item 5. A method for forming a protruding electrode for external connection according to item.