JPS6349378B2 - - Google Patents

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, gold bumps for electrodes of integrated circuits and polyimide coatings for surface protection have been formed 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 sectional view taken along line A-A' in FIG. 2.

As shown in FIG. 1, a Ti film 1 as an adhesive layer and a Pt film 2 as a barrier layer are deposited on the insulating film 5 of the wafer after the diffusion, insulating film formation, and wiring processes have been completed. The first bump 3 and the second bump 4 are formed with gold plating.

Next, as shown in FIGS. 2 and 3, a polyimide film 6 is formed to protect the surface and prevent the bumps from peeling off. After forming the polyimide film by coating on the wafer, the polyimide film on the second bumps 4 is removed by exposure and development, and is selectively removed so as to cover the ends of the first bumps 3. However, since the second bump 4 has a thickness of 10 to 25 μm and has an abnormally tight step, it is difficult to selectively remove the second bump 4 according to a desired pattern. It is often formed by exposing the other wafer surface.

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. Furthermore, since the first bumps 3 and a portion of the wafer other than the bumps are exposed, there is a drawback that surface protection is insufficient.

[Purpose of the invention]

An object of the present invention is to provide a method for manufacturing an integrated circuit in which the above-mentioned drawbacks are eliminated, the polyimide film sufficiently covers the end of the first bump, prevents the bump from peeling off, and also sufficiently plays the role of a surface protection film. It is about providing.

[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, a second metal film as a barrier layer, and a first metal film of Au on the insulating film of a wafer on which diffusion, an insulating film, and wiring have been formed. A first step of sequentially forming bumps, a second step of forming a polyimide film having openings on all or part of the first bumps, and applying a chemical agent to the entire surface of the wafer on which the polyimide film is formed. a third step of forming a third metal film made of a metal that can be etched by etching, and depositing a photoresist film over the entire surface of the wafer on which the third metal film is formed so as to overlap with the openings of the polyimide film. a fourth step of forming an opening; a fifth step of forming a second bump by electrolytic gold plating using the photoresist film as a mask and the third metal film as an electrode; The method includes a sixth step of removing the film using an organic remover that does not dissolve the film, and a step of etching away portions of the third metal film other than the bumps.

[Explanation of Examples]

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

FIGS. 4a to 4g are cross-sectional views showing the steps in order to explain an embodiment of the present invention.

As shown in FIG. 4a, on the insulating film 5 on the surface of the integrated circuit after the diffusion, insulating film and wiring processes are completed, a 0.1 μm Ti film 1 is placed as an adhesion layer between the bump and the insulating film.
0.1μm thick Pt as barrier layer between Ti and gold bumps
A film 2 and a first gold bump 3 are formed.

Next, as shown in FIG. 4b, a polyimide film is applied to the surface of the 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 Figure 4c, metals such as Pd, Ni, and Cu, which are easily etched by chemicals in later steps and are convenient as electrodes for gold plating, are used.
0.1 μm thick metal selected from the group consisting of
A Pd film 7 is formed on the entire surface by sputtering.

Next, as shown in FIG. 4d, a photoresist film 8 is coated on the entire surface, and then the photoresist film 8 is patterned to form openings 10 that overlap the openings 9 of the polyimide coating 6.

Next, as shown in Figure 4e, the previously formed
Using the Pd film 7 as an electrode, the photoresist film opening 1
A second bump 4 with a thickness of 20 μm is formed by electrolytic gold plating.
form.

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

Next, as shown in FIG. 4g, the portions of the Pd film 7 other than the second bumps are removed by etching with a Pd etching solution containing ferric chloride, hydrochloric acid, or the like.

Through the above steps, the gold 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 peeling from the insulating layer can therefore be reliably prevented. Further, for the same reason, the wafer surface is not exposed, so it can sufficiently serve as a protective film for the polyimide film.

Note that in the above embodiment, the first metal film is a Ti film,
Although a Pt film was used as the second metal film, it is not limited to this, and the first metal film may be Cr,
NiCr, Ta, Mo, second metal film: Pd, Ni
metal films can be applied as well.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to easily manufacture an integrated circuit with less peeling of bumps and a high surface protection effect.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an integrated circuit in a conventional process in which first and second bumps are 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 figure is A- in Figure 2.
A' sectional view and FIGS. 4a to 4g are sectional views shown in the order of steps for explaining an embodiment of the present invention. 1...Ti film, 2...Pt film, 3...first bump,
4... Second bump, 5... Insulating film, 6... Polyimide film, 7... Pd film, 8... Photoresist film,
9, 10... Opening part.

Claims (1)

[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 a wafer on which diffusion, an insulating film, and wiring have been formed. 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 consisting of the third metal film;
a fourth step of depositing a photoresist film over the entire surface of the wafer on which the metal film has been formed and forming an opening that overlaps with the opening of the polyimide film; using the photoresist film as a mask, forming the third metal film; a fifth step of forming a second bump by electrolytic gold plating using the metal film as an electrode; a sixth step of removing the photoresist film with an organic stripping agent that does not dissolve the polyimide film; A method of manufacturing an integrated circuit, comprising the step of etching away portions other than the bumps. 2 The first metal film is a Ti film, the second metal film is a Pt film,
A method for manufacturing an integrated circuit according to claim 1. 3 Metals that can be etched with chemicals include Pd, Ni,
Claim 1 selected from the group consisting of Cu
A method for manufacturing an integrated circuit as described in Section 1.