JPS6083350A - Manufacture of integrated circuit - Google Patents

Abstract

PURPOSE:To prevent the peeling of a bump by forming the thin first bump and forming a protective polyimide film. CONSTITUTION:A Ti film 1, a Pt film 2 and an Au first bump 3 are formed on an insulating film 5 on the surface of an integrated circuit. A polyimide film 6 is applied. A Pd film 7 is shaped on the whole surface through sputtering. A photo- resist film 8 is patterned to form an opening section 10. The film 7 is removed while using the film 8 as a mask. A second bump 4 is formed through electrolytic Au plating while using the film 7 as an electrode. The films 8, 7 are removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method for manufacturing an integrated circuit, and more particularly to a method for manufacturing an integrated circuit having gold bumps for electrodes serving as external terminals.

[Prior art]

Conventionally, the formation of Au bumps for electrodes of integrated circuits and polyimide coatings for surface protection has been carried out as shown in FIGS. 1 to 3.

Figure 1 is a cross-sectional view of an integrated circuit manufacturing process in which first and second bumps are formed on a wafer, and Figure 2 is a plan view of an integrated circuit in which a polyimide film is formed to protect the surface and prevent bumps from peeling off. , FIG. 3 is a cross-sectional view taken along the line A-A' in FIG. 2. As shown in FIG. Membrane 1
After the PT pattern film 2 serving as a barrier layer is completely deposited, the first bump 3 and the second bump 4 are formed thereon by Au plating.

Next, a polyimide coating 6 is formed on the gills shown in FIGS. 2 and 3 to protect the surface and prevent the bumps from peeling off.

After forming a polyimide film on the wafer, the polyimide film on the second bump 4 is removed by exposure and development, and is selectively removed so as to cover the end of the first bump 3. 2 The thickness of bump 4 is 10-25
Due to the thick and abnormally tight step height of μm, it is difficult to selectively remove the bump according to the desired pattern, and the edge of the first bump 3 is covered and not only one bump is missing, but also the waviness/surface other than the second bump 4 is exposed. It is often done.

In the integrated circuit formed in this manner, the ends of the first bumps 3 are not sufficiently covered, so that the polyimide coating 6 is useless in preventing the bumps from peeling off, which is the first role. Also the first
S has the disadvantage that the bump 3 and a part of the wafer other than the bump are exposed, so the surface protection is insufficient.
,Ta.

In addition, this type of integrated circuit may be required to be reliable under harsh conditions such as high temperatures, and in this case, the presence of dissimilar metals within the Au bump will lead to deterioration of strength and electrical characteristics. It had the disadvantage of leading to

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an integrated circuit that eliminates the above-mentioned drawbacks, allows the polyimide film to sufficiently cover the end of the first bump, sufficiently prevents the bump from peeling off, and is highly reliable even under harsh conditions. 0 [Structure of the Invention] The method for manufacturing an integrated circuit of the present invention includes forming a first metal film as an adhesion layer and a barrier layer on the insulating film of a wafer on which a diffusion region, an insulating film, and wiring have been formed. Second metal film and Au
a first step of sequentially forming first bumps on the first bag; a second step of forming a polyimide film having holes on all or part of the first bag; a third step of forming a third metal film made of a metal that can be etched with chemicals, and depositing a photoresist film over the entire surface of the wafer where the third metal film is formed, and forming the openings in the polyimide film. a fourth step of forming a smaller aperture overlapping the polyimide coating aperture; and a step of removing the third metal film within the aperture of the third metal film by etching. a sixth step of forming a second bump by performing electrolytic Au plating using the photoresist film as a mask and the third metal film as an electrode; and a sixth step of forming a second bump by dissolving the photoresist film into a polyimide film. The method includes a seventh step of removing the third metal film using an organic remover, and an eighth step of removing the third metal film by etching.

[Explanation of Examples]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 4(a) to 4(g) are cross-sectional views shown in order of steps for explaining an embodiment of the present invention.

As shown in FIG. 4(a), an If i film 1 with a thickness of 0.1 μm is placed on the insulating film 5 on the surface of the integrated circuit after completing the diffusion, insulating film and wiring process as an adhesion layer between the bumps and the insulating layer. 'p
O5 1 μm thick PT as a barrier layer between i and Au bumps.
A film 2 and a first bump 3 of Au are formed.

Next, as shown in FIG. 4(b), a polyimide film is applied to the surface of one wafer, and openings 9 for forming second bumps are formed on the first bumps 3. At this time, the ends of the first bumps 3 are formed to be reliably covered with the polyimide coating 6.

Next, as shown in FIG. 4(C), metals 1. Pd, Ni, QH
Pd with a thickness of 0.1 μm as a metal selected from the group consisting of
A film 7 is formed over the entire surface by sputtering.

Next, as shown in FIG. 4(d), after coating the entire surface with a photoresist film 8, a photoresist film is applied over the openings of the polyimide film so that the openings are smaller than the openings 9 of the polyimide film 6. 8 is patterned to form an opening 1o in the photoresist film.

Next, using the photoresist film 8 as a mask, the wafer is immersed in a Pd etching solution containing ferric chloride, hydrochloric acid, etc., and the Pd film exposed in the opening 10 is removed by selective etching.

Next, as shown in FIG. 4(e), the previously formed Pd
Using the membrane 7 as an electrode, a 20 μm thick second bump 4 is formed in the opening 1o by electrolytic Au metallization.

Next, as shown in FIG. 4(f), the photoresist film 8 on the wafer is removed using a stripping solution.

Next, as shown in FIG. 4(g), the Pd film 7 is removed by etching with a Pd etching solution using ferric chloride, hydrochloric acid, or the like.

Through the above steps, the Au bumps of the electrodes and the protective polyimide coating can be formed.

The polyimide film formed above is formed after the thin first bump is formed, not after the second bump is formed as in the conventional case, so the photoresist patterning can be carried out accurately, and the end of the first bump can be covered with the polyimide film. Sufficient coverage can be achieved, and therefore, peeling from the insulating layer can be reliably prevented. Further, for the same reason, since the surface of the wafer is not exposed, it can also serve as a protective film for the polyimide film.

Note that in this example, the Pd film, which is the third metal film formed on the first bump, was removed before forming the second bump. Although the object of the present invention can be achieved even if a Pd film is interposed between the first bump and the second bump, when this integrated circuit is exposed to harsh conditions such as high temperatures, mechanical strength and electrical characteristics deteriorate. However, in this embodiment, since the bumps are removed before forming the second bumps, a highly reliable integrated circuit can be obtained.

In the above embodiment, a T1 film is used as the first metal film and a Pt film is used as the second metal film, but the invention is not limited thereto, and the first metal film may be Or or Ni0r.

As the Ta, Mo, and second metal films, metal films of Pd and Ni can be similarly applied. □ [Effects of the Invention] As described above, according to the present invention, it is possible to easily manufacture a highly reliable integrated circuit with less bump peeling and a large surface protection effect.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an integrated circuit in a conventional process in which a second bank on a first bump is formed on a wafer, FIG. 2 is a plan view of a conventional integrated circuit in which a polyimide film is formed on the surface, and FIG. The figures are A and -A' cross-sectional views in Figure 2, and Figures 4 (a) to (g).
) are sectional views showing the order of steps for explaining one embodiment of the present invention. 1...Ti film, 2...PT film, 3...
...First bump, 4...Second bump, 5.
...Insulating film, 6...Polyimide coating, 7
... Pd film, 8 ... Photoresist film,
9.10... Opening part. Figure 1 Rin 22 Figure 4 Old

Claims (3)

[Claims] (1) A first metal film as an adhesion layer, a second metal film as a barrier layer, and a first bump of Au are sequentially formed on the insulating film of the wafer on which the diffusion region, insulating film, and wiring have been formed. a first step, and a second step of forming a polyimide film having openings on all or part of the first bump;
A third step of forming a third metal film made of a metal that can be treated with chemicals on the entire surface of the polyimide film, and forming a resist layer on the wafer on which the third metal film is formed. a fourth step of coating the entire surface of the polyimide film and forming apertures smaller than the apertures of the polyimide film overlapping the polyimide film apertures; a fifth step of etching and removing the metal film; a sixth step of forming a second bump by performing electrolytic Au etching using the photoresist film as a mask and the third metal film as an electrode; A method for manufacturing an integrated circuit, comprising: a seventh step of removing the photoresist film with an organic remover that does not dissolve the polyimide film; and an eighth step of removing the third metal film by etching. . (2) The method for manufacturing an integrated circuit according to claim (1), wherein the first metal film is a Ti film and the second metal film is a PT film. (3) Metals that can be etched with chemicals are pa and Ni. A method for manufacturing an integrated circuit according to claim (1) or (2), wherein the metal is selected from the group consisting of Ou.