JP2717835B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of forming a bump electrode for connecting a semiconductor chip to a package. In a method of manufacturing a semiconductor device in which a bump electrode is formed on a substrate, a first resist film having a predetermined pattern is formed in a region excluding an electrode forming portion of the substrate, and a first resist film is formed. Forming a second resist film thicker and wider than the end thereof, and forming a bump electrode made of a first conductive material on an electrode forming portion using the second resist film as a mask; Forming the second resist film, removing the second resist film, and using the first resist film as a mask, around a bump electrode, and at an end of the first resist film. A step of plating a metal film made of a second conductive material that is more resistant to corrosion than the first conductive material, and a step of removing the first resist film. Including and including the manufacturing method.

[Industrial applications]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming a bump electrode for connecting a semiconductor chip to a package.

[Conventional technology]

In recent years, high integration, high reliability of semiconductor integrated circuits (IC),
With the demand for cost reduction and the like, various plating techniques are required.

For example, it is necessary to form a box-shaped straight bump electrode for high integration, a corrosion-resistant plating film is required for high reliability, and a cheap plating film is required for cost reduction. I have.

Conventionally, a resist pattern is used as a mask to selectively plate a semiconductor substrate.However, if the resist is thin, plating is applied in the horizontal direction, and the plating becomes a mushroom shape. Is used. Further, gold (Au) plating having corrosion resistance is used for plating for high reliability.

However, the use of Au plating is costly, and Au plating has the drawback that it cannot be plated at high speed and takes too much time.

The use of copper (Cu) plating reduces costs and improves throughput, but because Cu has poor corrosion resistance,
There was a problem that high reliability could not be obtained.

Therefore, as shown in FIGS. 3 (a) and 3 (b), a thick film resist 2 is formed in a region other than the electrode portion forming region of the substrate 1, and using the thick film resist 2 as a mask, the Cu bump electrode 3 is formed. In the case where an Au film 4 is formed on the bump electrode 3 by Au plating (FIG. 2A), and then the thick film resist 2 is peeled off (FIG. 2B). Then, the side wall of the bump electrode 3 is not Au-plated and is corroded.

[Problems to be solved by the invention]

That is, in order to form a highly reliable bump electrode, Au
When Cu was used, cost reduction and throughput could not be improved, and when Cu was used, there was a problem in high reliability.

Therefore, an object of the present invention is to provide a highly reliable method for forming a bump electrode which can reduce cost and improve throughput.

[Means for solving the problem]

The object is to provide a method of manufacturing a semiconductor device in which a bump electrode is formed on a substrate, wherein a first resist film having a predetermined pattern is formed in a region excluding an electrode forming portion of the substrate, and a first resist film is formed on the first resist film. A step of forming a second resist film that is thick and extends beyond the end thereof; and a step of forming a bump electrode made of a first conductive material in an electrode forming portion using the second resist film as a mask. Stripping the second resist film, and using the first resist film as a mask, around the bump electrode and up to the end of the first resist film, more corrosion resistant than the first conductive material. A method for manufacturing a semiconductor device, comprising: a step of plating a metal film made of a second conductive material having a certain property; and a step of removing the first resist film.

[Action]

 1 (a) to 1 (c) are diagrams for explaining the principle of the present invention.

First, as shown in FIG. 1A, a first resist film 12 is formed in a region excluding an electrode forming portion of a substrate 11, and a second resist film 13 is formed on the first resist film 12 in a second step. After the first resist film 12 is formed sufficiently thicker than the first resist film 12, a bump electrode 14 made of a first conductive material is formed on the electrode forming portion using the second resist film 13 as a mask.

Next, as shown in FIG.
Then, a metal film 15 made of a second conductive material, which is more resistant to corrosion than the bump electrode 14 of the first conductive material, is plated around the bump electrode 14 using the first resist film 12 as a mask.

Next, as shown in FIG.
Is peeled off.

Through the above steps, the bump electrode 14 is formed around which the metal film 15 having corrosion resistance is plated.

That is, according to the present invention, the bump electrode made of the first conductive material such as Cu having a high plating rate is formed on the electrode forming portion of the substrate 11.
By forming a metal film 15 made of a second conductive material such as Au having corrosion resistance around the bump electrode 14, there is no problem in terms of the corrosion resistance of the bump electrode. Also, cost and throughput are improved.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings.

2 (a) to 2 (d) are cross-sectional views showing a manufacturing process of the bump electrode according to the embodiment of the present invention.

First, as shown in FIG.
An aluminum (Al) wiring 22 is formed, and a PSG film 23 having a thickness of about 1.0 μm, a SiN film 24 having a thickness of about 0.3 μm, and a PI film 25 having a thickness of about 2.0 μm are sequentially formed as a cover film. Then, an opening 26 is formed as an electrode portion.

Next, as shown in FIG. 4B, a titanium (Ti) film 27 is formed as a barrier metal on the entire surface by 5000 ° and a palladium (Pd) film 28 is formed by 3000 ° on the entire surface by sputtering. Is patterned with a first resist film 29 having a thickness of about 1 to 2 μm (for example, HPR204 which is a novolak-based resist manufactured by Fuji Hunt Co., Ltd.)
A second resist film (for example, BMR-SF1000 which is an acrylic resist manufactured by Tokyo Ohka Co., Ltd.) 30 of about 30 μm is applied and patterned. At this time, the first resist film 29
The opening is formed slightly larger than the opening of the second resist film 30. Thereafter, Cu plating is performed using the second resist film 30 as a mask, and a bump electrode 31 having a height of about 25 μm is formed in a box shape in the opening of the electrode forming portion.

Next, as shown in FIG.
Is subjected to wet stripping (for example, a BMR stripping solution manufactured by Tokyo Ohka Co., Ltd.) using a wet stripping solution dedicated to an acrylic resist, and then Au plating is performed using the first resist film 29 as a mask to form a film on the surface of the bump electrode 31. A about 2.0μm thick
The u film 32 is formed.

Next, as shown in FIG.
Is removed by dry stripping or wet stripping by ashing (for example, 502 stripper manufactured by Tokyo Ohka Co., Ltd.). Thereafter, using the Au film 32 as a mask, the Pd film 28 and the Ti film 27, which are barrier metals, are etched with aqua regia and ammonia hydrogen peroxide.

According to the above method, a bump electrode 31 made of a conductive material such as Cu having a high plating rate is formed on the electrode forming portion of the substrate 21, and a corrosion-resistant Au film 32 is formed around the entire bump electrode 31. The plating eliminated the problem in terms of the corrosion resistance of the bump electrode 31. Further, in this embodiment, Au
Since the plating solution is about 5 times as expensive as the Cu plating solution, the cost is 1/5 and the throughput is 1μm / 4 for Au plating.
Min, Cu plating improved 2-3 times at 1 μm / 1.5 min.

In the above embodiment, the Au around the bump electrode 31 made of Cu is used.
Although the film 32 is formed, a metal film made of a second conductive material having higher corrosion resistance may be formed around the first conductive material having a high plating rate.

Further, the bump electrode formed by the method of the present invention can be applied to a TAB method for bonding to a lead frame wiring, a CCB method by flip chip bonding, or the like.

〔The invention's effect〕

As described above, according to the present invention, a metal film made of a corrosion-resistant second conductive material is plated around a bump electrode made of a first conductive material formed on an electrode forming portion, There is an effect that the corrosion resistance of the bump electrode is improved, and the cost and the throughput are also improved.

[Brief description of the drawings]

FIGS. 1 (a) to 1 (c) are explanatory diagrams of the principle of the present invention, FIGS. 2 (a) to 2 (d) are cross-sectional views of a bump electrode manufacturing process according to an embodiment of the present invention, FIGS. FIG. 2B is a cross-sectional view illustrating a manufacturing process of a conventional bump electrode. In the figure, 11 is a substrate, 12 is a first resist film, 13 is a second resist film, 14 is a bump electrode, 15 is a metal film, 21 is a wafer substrate, 22
Is an Al wiring, 23 is a PSG film, 24 is a SiN film, 25 is a PI film, 26 is an opening, 27 is a Ti film, 28 is a Pd film, 29 is a first resist film, 30
Denotes a second resist film, 31 denotes a bump electrode, and 32 denotes an Au film.

Claims (1)

(57) [Claims] 1. A method of manufacturing a semiconductor device, wherein a bump electrode is formed on a substrate, wherein a first resist film having a predetermined pattern is formed in a region excluding an electrode forming portion of the substrate. Forming a second resist film (13) thicker than the first resist film (12) and extending beyond the end thereof on the first resist film (12); A) forming a bump electrode (14) made of a first conductive material on an electrode forming portion using the mask as a mask; (b) stripping the second resist film (13); Is used as a mask, around the bump electrode (14) and up to the end of the first resist film (12), a metal film (15) made of a second conductive material that is more resistant to corrosion than the first conductive material. ) And a step of stripping the first resist film (12). The method of manufacturing a semiconductor device according to claim.