JPH06342796A - Forming method of bump electrode - Google Patents

Abstract

PURPOSE:To provide a method of forming a bump electrode which is high in reliability, excellent in adhesion to an electrode pad, and hardly separated from the pad. CONSTITUTION:By a wafer process, an electroplating conductive layer 4 of metal which is easily etched is formed on all the surface of a semiconductor substrate 1 where an electrode pad 2 and a surface protective film 3 are provided a first photoresist film 5 is applied, only a bump electrode forming part is removed, and a first contact hole is formed. Then, base metal layers 6, 7, and 8 are formed on the bump electrode forming part and the first photoresist film 5, a second photoresist film 9 is applied, the resist film 9 is removed to form a second contact hole slightly smaller than the first contact hole, and a bump electrode 10 is formed by electroplating. The first and the second photoresist film, 5 and 9, are removed, and then electroplating conductive layer 4 is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming, on a semiconductor substrate, a protruding electrode used for connecting wiring on the surface of the substrate and an external circuit.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a protruding electrode used for connecting the wiring of the substrate and an external circuit on a semiconductor substrate, a region other than the protruding electrode forming region of the semiconductor substrate is covered with a photoresist film, After forming a metal layer on the entire surface of the chip by vapor deposition or sputtering, a method of forming a protruding electrode by etching the photoresist film by a method such as lift-off, or by coating the area other than the protruding electrode formation region of the semiconductor substrate with the photoresist film. A method is known in which electroplating is selectively performed and metal is deposited only in a region not covered with a photoresist film to form a protruding electrode.

Next, an example of a conventional method of forming the protruding electrode will be described with reference to FIG. First, an electrode pad 102 is formed on a predetermined portion of the surface of a semiconductor substrate 101 formed through a normal wafer process.
The surface protective film 103 is formed on the other portions. Then, an adhesive layer is formed on the surface protective film 103 and the surface of the electrode pad 102.
A bump electrode base metal layer having good adhesion, which is composed of 104, the diffusion prevention layer 105 and the plating layer 106, is formed on the entire surface of the semiconductor substrate by vapor deposition or sputtering. Next, after the projection electrode base metal layers 104, 105 and 106 other than the projection electrode formation portion are covered with the photoresist film 107, the projection electrode base metal layer
A protruding electrode 108 is formed by electroplating using 104, 105 and 106 as conductive paths. Finally, by using the protruding electrode 108 as a mask, the photoresist film 107 and the extra protruding electrode underlying metal layers 104 1, 105 and 106 are removed by etching to complete the protruding electrode on the semiconductor substrate.

[0004]

By the way, in the conventional method of forming a protruding electrode shown in FIG. 8, when the underlying metal layer is removed with an etching solution in the final step, the underlying metal layer portion is formed by laminating different metals. Since it is formed, over-etching is likely to occur due to the local cell action, and precise etching control is difficult, and as shown in FIGS. 9A and 9B, etching may proceed to the lower part of the protruding electrode 108. Yes, in this case, the protruding electrode 108 is easily peeled off,
There is a risk of peeling.

The present invention has been made in order to solve the above problems in the conventional method of forming the protruding electrodes for the semiconductor substrate, and has a highly reliable projection that has good adhesiveness to the electrode pad and is not likely to peel off. It is an object to provide a method for forming an electrode.

[0006]

In order to solve the above problems, the present invention forms a surface protective film on the surface portion of the semiconductor substrate other than the electrode pads formed on the predetermined portion of the surface of the semiconductor substrate. After that, a step of forming a conductive layer for electroplating on the electrode pad and the surface protection film, a step of forming a first photoresist film on the conductive layer for electroplating, and a step of forming a protruding electrode on the electrode pad A step of removing the first photoresist film in a portion to be formed to form a first contact hole, and an exposed portion of the electroplating conductive layer formed on the electrode pad and the first photoresist film. A step of forming a base metal layer on the base metal layer, a step of forming a second photoresist film on the base metal layer, and a step of removing the second photoresist film and forming the first contact layer on the electrode pad. Forming a second contact hole slightly smaller than the first contact hole in the through hole, and using the second photoresist film as a mask to form the conductive layer for electroplating in the second contact hole. Forming a bump electrode on the underlying metal layer on the electrode pad by electroplating, and removing the underlying metal layer on the first photoresist film together with the first and second photoresist films. And a step of removing the electroplating conductive layer on the surface of the semiconductor substrate by using the underlying metal layer on the electrode pad as a mask, thereby forming the protruding electrode.

In the above-mentioned method of forming the protruding electrode, the underlying metal layer is formed on the electroplating conductive layer exposed in the first contact hole of the first photoresist film, so that the etching is performed in the final step. It is only necessary to remove the conductive layer for electroplating, which eliminates the need for etching the underlying metal layer, which is difficult to etch, and therefore a highly reliable bump electrode can be formed by a simple process.

[0008]

EXAMPLES Next, examples will be described. 1-7
FIG. 6 is a diagram showing a manufacturing process for explaining an example of the method for forming the protruding electrode according to the present invention. First, as shown in FIG. 1, an electrode pad 2 is formed on a predetermined portion of the surface of a semiconductor substrate 1 formed through a normal wafer process, and a surface protective film 3 is formed on the surface of the semiconductor substrate 1 other than the electrode pad 2. After the formation of Al, the conductive layer 4 for electroplating is formed on the entire surface by vapor deposition or sputtering of Al, Ni, etc., which can be easily etched.
To form. Next, as shown in FIG. 2, a first photoresist film 5 is applied to a thickness of, for example, 5 μm to 25 μm, and then the first electroconductive layer 4 for electroplating which reaches the electroplating conductive layer 4 only by the photolithography is formed. The contact hole 5a is formed. Then, as shown in FIG.
On the surface of the electroconductive layer 4 for electroplating and the surface of the first photoresist film 5 exposed in the contact hole 5a of the adhesive layer 6 with a combination of Cr, Cu, Ni, Au, Ti, W, etc. A base metal layer for the protruding electrode, which is composed of the layer 7 and the plated layer 8, is formed by vapor deposition, sputtering or the like.

Next, as shown in FIG. 4, a second photoresist film 9 is applied to the entire surface of the semiconductor substrate, and photolithography is performed to reach the protruding electrode forming metal layers 6, 7, 8 for the protruding electrodes. , A second slightly smaller than the first contact hole 5a of the first photoresist film 5
Contact hole 9a is formed. Next, as shown in FIG. 5, using the electroplating conductive layer 4 as a conductive path, the protruding electrode 10 made of Au, Ag, Cu, Pb-Sn or the like is formed on the base metal layer.
It is formed by electroplating. Then, after forming the bump electrode 10, as shown in FIG. 6, the first and second photoresist films 5 and 9 are removed. At this time, the unnecessary underlying metal layer 6, formed on the surface of the first photoresist film 5,
7, 8 are removed by the lift-off method when removing the first photoresist film 5. Finally, as shown in FIG.
The electroplating conductive layer 4 is removed by wet or dry etching using the underlying metal layers 6, 7, and 8 as masks,
The semiconductor substrate 1 having the protruding electrodes 10 formed on the electrode pads 2 is obtained.

In this method of forming the protruding electrode, the protruding electrode 10 can be formed by a simple process by electroplating, and the electroplating conductive layer 4 and the underlying metal layers 6, 7, 8 are formed.
Since it is formed separately, it is not necessary to etch the underlying metal layers 6, 7 and 8 which are difficult to etch, and the protruding electrode 10 is completed by removing the electroplating conductive layer 4 which is easy to etch in the final step. Therefore, the occurrence of peeling of the protruding electrode due to overetching of the underlying metal layer is prevented, and a highly reliable protruding electrode can be formed by a simple process.

[0011]

As described above on the basis of the embodiments, according to the present invention, it is sufficient to remove the electroplating conductive layer which is easy to etch in the final step, and to remove the underlying metal layer which is difficult to etch. Since etching is unnecessary, it is possible to form a highly reliable bump electrode that does not cause peeling or the like in a simple process.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process for explaining an example of a method for forming a bump electrode according to the present invention.

FIG. 2 is a diagram showing a manufacturing process that follows the manufacturing process shown in FIG.

FIG. 3 is a diagram showing a manufacturing process that follows the manufacturing process shown in FIG. 2;

FIG. 4 is a diagram showing a manufacturing process that follows the manufacturing process shown in FIG. 3;

FIG. 5 is a diagram showing a manufacturing process that follows the manufacturing process shown in FIG. 4;

FIG. 6 is a diagram showing a manufacturing process that follows the manufacturing process shown in FIG. 5;

FIG. 7 is a diagram showing a manufacturing process that follows the manufacturing process shown in FIG. 6;

FIG. 8 is a diagram showing one manufacturing process for explaining an example of the conventional method of forming the protruding electrode.

FIG. 9 is a diagram for explaining a problem of a protruding electrode formed by a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Electrode pad 3 Surface protective film 4 Electroconductive layer 5 for electroplating 5 First photoresist film 5a First contact hole 6 Adhesive layer 7 Diffusion prevention layer 8 Plating layer 9 Second photoresist film 9a Second Contact hole 10 Projection electrode

Claims (1)

[Claims] 1. A surface protective film is formed on a surface portion of the semiconductor substrate other than the electrode pads formed on a predetermined portion of the surface of the semiconductor substrate, and then a conductive layer for electroplating is formed on the electrode pad and the surface protective film. And a step of forming a first photoresist film on the electroplating conductive layer,
A step of removing a first photoresist film on a portion of the electrode pad where a protruding electrode is formed to form a first contact hole; and an exposed portion of a conductive layer for electroplating formed on the electrode pad. And a step of forming a base metal layer on the first photoresist film, a step of forming a second photoresist film on the base metal layer, and a step of removing the second photoresist film on the electrode pad. The first formed
Forming a second contact hole slightly smaller than the first contact hole in the contact hole, and using the second photoresist film as a mask to form the electroplating conductive layer in the second contact hole. Forming a protruding electrode on the underlying metal layer on the electrode pad by electroplating to form a conductive path; and removing the underlying metal layer on the first photoresist film together with the first and second photoresist films. And a step of removing the electroplating conductive layer on the surface of the semiconductor substrate using the underlying metal layer on the electrode pad as a mask.