JP4134770B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device having rewiring and columnar electrodes, and a method for manufacturing the same.
[0002]
[Prior art]
A conventional semiconductor device is called a CSP (chip size package), in which a rewiring made of copper is provided on a semiconductor substrate, and a columnar electrode made of copper is provided on a connection pad portion of the rewiring. Yes (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 5-218042
[Problems to be solved by the invention]
By the way, in the conventional semiconductor device, even if the sealing film is provided between the columnar electrodes on the semiconductor substrate including the rewiring, a positive voltage is applied when moisture in the use environment penetrates the sealing film. There is a problem in that the copper ions dissolved from the columnar electrodes that have moved move and deposit on the columnar electrodes to which a negative voltage is applied, so that a short circuit may occur due to so-called ion migration.
In view of the above, an object of the present invention is to provide a semiconductor device and a method for manufacturing the same that can prevent a short circuit due to so-called ion migration.
[0005]
[Means for Solving the Problems]
The invention according to claim 1 is the rewiring provided on the base metal layer provided on the semiconductor substrate, the rewiring provided on the base metal layer, and the connection pad portion of the rewiring. And a anodic oxide film provided on at least the upper surface of the outer peripheral surface of the columnar electrode and the rewiring.
According to a second aspect of the present invention, in the first aspect of the present invention, a sealing film is provided between the columnar electrodes on the semiconductor substrate including the rewiring.
The invention described in claim 3 includes a step of forming a base metal layer on one surface of a semiconductor substrate, a step of forming a rewiring on the base metal layer using the base metal layer as a plating current path, and the base metal. Forming a columnar electrode of the same material as the rewiring on the connection pad portion of the rewiring using a layer as a plating current path, and anodizing the columnar electrode and the rewiring with the underlying metal layer as one electrode And a step of forming a film.
According to a fourth aspect of the present invention, in the third aspect of the present invention, the step of forming a sealing film on the semiconductor substrate including the anodic oxide film and the anodic oxide film on the upper surface of the columnar electrode are removed. And exposing the upper surface of the columnar electrode.
According to the present invention, since the anodic oxide film is provided on the outer peripheral surface of the columnar electrode and at least the upper surface of the rewiring, it is possible to prevent a short circuit due to so-called ion migration.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a cross-sectional view of a semiconductor device as an embodiment of the present invention. This semiconductor device includes a silicon substrate (semiconductor substrate) 1. An integrated circuit (not shown) is provided at the center of the upper surface of the silicon substrate 1, and a plurality of connection pads 2 made of aluminum-based metal are provided connected to the integrated circuit at the periphery of the upper surface.
[0007]
An insulating film 3 made of silicon oxide, silicon nitride, or the like and a protective film (insulating film) 4 made of polyimide, benzocyclobutene (BCB), or the like are provided on the upper surface of the silicon substrate 1 excluding the central portion of the connection pad 2. . A central portion of the connection pad 2 is exposed through an opening 5 provided in the insulating film 3 and the protective film 4.
[0008]
A base metal layer 6 is provided from the upper surface of the connection pad 2 exposed through the opening 5 to a predetermined location on the upper surface of the protective film 4. A rewiring 7 made of copper is provided on the upper surface of the base metal layer 6. A columnar electrode 8 made of copper is provided on the upper surface of the connection pad portion of the rewiring 7. An anodic oxide film 9 is provided on the upper surface of the rewiring 7 and the outer peripheral surface of the columnar electrode 8.
[0009]
On the upper surface of the protective film 4 including the anodic oxide film 9 on the rewiring 7, the upper surface of the sealing film 10 made of epoxy resin is flush with the upper surface of the columnar electrode 8 and the anodic oxide film 9 on the outer peripheral surface thereof. It is provided to become. Therefore, the upper surfaces of the columnar electrode 8 and the anodic oxide film 9 on the outer peripheral surface thereof are exposed. Solder balls 11 are provided on the upper surfaces of the exposed columnar electrodes 8 and the anodic oxide film 9 on the outer peripheral surface thereof.
[0010]
Next, an example of a method for manufacturing this semiconductor device will be described. First, as shown in FIG. 2, a connection pad 2 made of an aluminum-based metal is formed on the upper surface of a silicon substrate 1 in a wafer state, and an insulating film made of silicon oxide or the like in a region excluding the central portion of the connection pad 2 on the upper surface. 3 and a protective film 4 made of polyimide or the like is formed, and the connection pad 2 is exposed through the opening 5 formed in the insulating film 3 and the protective film 4.
[0011]
Next, as shown in FIG. 3, a base metal layer 6 is formed on the upper surface of the protective film 4 including the upper surface of the connection pad 2 exposed through the opening 5. In this case, although not shown in detail, the base metal layer 6 is obtained by forming a copper layer by sputtering on a titanium layer formed by sputtering. Note that the base metal layer 6 may be only a copper layer formed by electroless plating.
[0012]
Next, the first plating resist film 21 is patterned on the upper surface of the base metal layer 6. In this case, an opening 22 is formed in the first plating resist film 21 in a region corresponding to the rewiring 7 formation region. Next, by performing electrolytic plating of copper using the base metal layer 6 as a plating current path, the rewiring 7 is formed on the upper surface of the base metal layer 6 in the opening 22 of the first plating resist film 21. Next, the first plating resist film 21 is peeled off.
[0013]
Next, as shown in FIG. 4, a second plating resist film 23 is patterned on the upper surface of the base metal layer 6 including the rewiring 7. In this case, an opening 24 is formed in the second plating resist film 23 in a region corresponding to the connection pad portion of the rewiring 7. Next, the columnar electrode 8 is formed on the upper surface of the connection pad portion of the rewiring 7 in the opening 24 of the second plating resist film 23 by performing copper electroplating using the base metal layer 6 as a plating current path. Next, the second plating resist film 23 is peeled off.
[0014]
Next, as shown in FIG. 5, an anodic oxidation resist film 25 is patterned on the upper surface of the underlying metal layer 6 exposed without being covered by the rewiring 7. Next, when the base metal layer 6 is a plus electrode, a platinum electrode (not shown) is a minus electrode, and anodization is performed using a 0.01 WT% aqueous citric acid solution as an anodizing electrolyte, the columnar electrode 8 An anodized film 9 is formed on the surface and the upper surface and side surfaces of the rewiring 7.
[0015]
Next, the resist film 25 for anodic oxidation is peeled off, and then unnecessary portions of the base metal layer 6 are removed by etching using the anodic oxide film 9 as a mask. As shown in FIG. The metal layer 6 remains. Next, as shown in FIG. 7, a sealing film 10 made of epoxy resin or the like is formed on the upper surface of the protective film 4 including the anodic oxide film 9 so that the thickness thereof is slightly larger than the height of the columnar electrode 8. To do. Therefore, in this state, the upper surface of the anodic oxide film 9 on the columnar electrode 8 is covered with the sealing film 10.
[0016]
Next, by polishing and removing the upper surface side of the sealing film 10 and at least the anodic oxide film 9 on the columnar electrode 8, as shown in FIG. 8, the columnar electrode 8 and the anodic oxide film 9 on the outer peripheral surface thereof are removed. The upper surface is exposed, and the exposed columnar electrode 8 and the upper surface of the anodic oxide film 9 on the outer peripheral surface thereof are substantially flush with the upper surface of the sealing film 10. Next, as shown in FIG. 9, solder balls 11 are formed on the upper surfaces of the columnar electrodes 8 and the anodic oxide film 9 on the outer peripheral surface thereof. Next, as shown in FIG. 10, after a dicing process, a plurality of semiconductor devices shown in FIG. 1 are obtained.
[0017]
In the semiconductor device thus obtained, the occurrence of migration on the outer peripheral surface of the columnar electrode 8 and the upper surface of the rewiring 7 is suppressed by the anodic oxide film 9 on the outer peripheral surface of the columnar electrode 8 and the upper surface of the rewiring 7. Therefore, a short circuit due to so-called ion migration is less likely to occur. Further, the adhesion of the sealing film 10 made of epoxy resin or the like to the anodic oxide film 9 is better than that of the copper layer alone, and therefore the sealing film 10 is formed on the outer peripheral surface of the columnar electrode 8 and the rewiring 7. It can be made difficult to peel from the upper surface.
[0018]
In addition, after forming the rewiring 7 on the upper surface of the base metal layer 6 in the opening 22 of the first plating resist film 21 illustrated in FIG. 3, the first plating resist film 21 remains without being peeled off. By patterning the second plating resist film 23 having the opening 24 and performing electrolytic plating using the base metal layer 6 as a plating current path, the columnar electrode 8 is formed in the opening 24 of the second plating resist film 23. Then, the second plating resist film 23 may be peeled off to form the anodic oxide film 9 on the upper surface of the rewiring 7 and the surface of the columnar electrode 8.
[0019]
This manufacturing method also results in the state shown in FIG. 5 (however, the anodic oxidation resist film 25 in FIG. 5 is replaced with the first plating resist film 21), and thereafter, the same process as described above is performed. Therefore, it is possible to reduce one photolithography process. In the above manufacturing method, if the first plating resist film 21 is a positive type and the second plating resist film 23 is a negative type, the first plating resist film 21 is etched by the etching solution of the second plating resist film 23. Since this is not done, the work can be made more reliable.
[0020]
In the above embodiment, the rewiring is one layer. However, the rewiring may be a multi-layer. In that case, the anodic oxide film is not limited to the rewiring on which the columnar electrodes are formed, but each layer as necessary. The rewiring may be formed.
[0021]
【The invention's effect】
As described above, according to the present invention, since the anodic oxide film is provided on the outer peripheral surface of the columnar electrode and at least the upper surface of the rewiring, it is possible to prevent a short circuit due to so-called ion migration.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a semiconductor device as one embodiment of the present invention.
FIG. 2 is a cross-sectional view of an initial manufacturing process in manufacturing the semiconductor device shown in FIG. 1;
FIG. 3 is a cross-sectional view of the manufacturing process following FIG. 2;
FIG. 4 is a cross-sectional view of the manufacturing process following FIG. 3;
FIG. 5 is a cross-sectional view of the manufacturing process following FIG. 4;
6 is a cross-sectional view of the manufacturing process following FIG. 5. FIG.
7 is a cross-sectional view of a manufacturing step that follows FIG. 6. FIG.
FIG. 8 is a cross-sectional view of the manufacturing process following FIG. 7;
FIG. 9 is a cross-sectional view of the manufacturing process following FIG. 8;
10 is a cross-sectional view of a manufacturing step that follows FIG. 9; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Connection pad 3 Insulating film 4 Protective film 5 Opening 6 Base metal layer 7 Rewiring 8 Columnar electrode 9 Anodized film 10 Sealing film 11 Solder ball 21 First plating resist film 23 Second plating resist film 25 Anodizing resist film

Claims (4)

A base metal layer provided on a semiconductor substrate, a rewiring provided on the base metal layer, a columnar electrode of the same material as the rewiring provided on a connection pad portion of the rewiring, and A semiconductor device comprising: an outer peripheral surface of a columnar electrode; and an anodized film provided on at least an upper surface of the rewiring.   2. The semiconductor device according to claim 1, wherein a sealing film is provided between the columnar electrodes on the semiconductor substrate including the rewiring. Forming a base metal layer on one surface of the semiconductor substrate; forming a rewiring on the base metal layer using the base metal layer as a plating current path; and rewiring the base metal layer as a plating current path. on the connection pad portion, said to have a step of forming a columnar electrode redistribution same material, and forming the columnar electrode and the anodic oxide film to the rewiring of the underlying metal layer as one electrode A method for manufacturing a semiconductor device.   4. The method according to claim 3, wherein a sealing film is formed on the semiconductor substrate including the anodic oxide film, and the anodic oxide film on the upper surface of the columnar electrode is removed to expose the upper surface of the columnar electrode. A method of manufacturing a semiconductor device.

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