JPH01187949A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the defective coverage of a barrier metallic layer, to fine a bump electrode and to obtain a method of forming the edge shape of a polyimide group resin layer preventing the generation of a crack in a cover film, by extending and forming the edge of the polyimide layer up to the upper section of an aluminum pad. CONSTITUTION:When a bump electrode is shaped onto a semiconductor chip, the upper section of a semiconductor substrate 1, in the specified region of the surface of which a metallic pad 2 is formed, is coated with cover films 10, 11, and a first contact window is shaped onto the fixed region of the metallic pad 2. A polyimide group resin layer 8 is formed onto the cover films 10, 11 including the inside of said first contact window, and a second contact window is shaped into said first contact window. A barrier metallic layer 4 is formed onto the polyimide group resin layer 8 containing the inside of said second contact window, a metallic bump 5 is shaped into a prescribed region on the barrier metallic layer 4, and the barrier metallic layer 4 is etched, using the metallic bump 5 as a mask.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a method for manufacturing an edge shape of a cover film formed on the surface of a semiconductor element when forming a bump electrode, which improves poor coverage of a barrier metal layer, and improves the coverage of a bump electrode. The objective was to provide a method for manufacturing polyimide resin with an edge shape that enables miniaturization of electrodes and also prevents the occurrence of cranking of the cover film.The semiconductor substrate on which metal pads are formed is covered with a cover film. a step of forming a first contact window on a predetermined region of the metal pad; and a step of forming a second contact window within the first contact window after forming a polyimide resin layer on the entire surface; A method characterized by comprising the steps of forming a barrier metal layer on the entire surface, forming metal bumps in a predetermined region on the barrier metal layer, and etching the barrier metal layer using the metal bumps as a mask. [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for manufacturing an edge shape of a cover film formed on the surface of a semiconductor element when forming a bump electrode.

[Conventional technology]

TA B is one of the high-density, multi-pin LSI mounting methods.
(Tape Automated Bonding) technology development is being actively carried out. The TAB method is a method in which metal protrusions, so-called bumps, are formed on aluminum pads using a wafer process, and leads are bonded onto the bumps.

FIG. 2 shows a cross-sectional view of the manufacturing process of a conventional bump electrode. The conventional manufacturing process of bump electrodes will be explained below with reference to FIG.

First, as shown in FIG. 2(a), an aluminum pad 2 is formed in a predetermined area on a semiconductor substrate 1 on which a semiconductor element is formed. Next, a cover film 3 made of PSG (phosphosilicate glass) or the like is formed to a thickness of approximately 1 μm over the entire surface, and then the cover film on the aluminum pad 2 is removed to form a contact window 7. Next, a barrier metal layer 4 is sputtered onto the cover film 3 including the contact window portion by a method such as a sputtering method.

This barrier metal layer 4 is provided to prevent the gold bumps that will be formed later from reacting with the aluminum pad 2 to produce high-resistance products, and to improve the adhesion with the gold bumps. It consists of two layers of platinum.

Next, as shown in Fig. 2, the surface has a thickness of approximately 20 mm.
After forming a resist layer 6 of ~30 μm, a window is opened on the aluminum pad 2 by photolithography.

Next, electroplating is performed using the barrier metal layer 4 as a plating electrode to form the gold bumps 5 to a thickness of about 15 to 30 μm.
m form.

Finally, as shown in FIG. 2 (C1), after peeling off the resist layer 6, the barrier metal layer 4 is etched using the gold bumps 5 as a mask.Aqua regia or hydrofluoric acid is used as the etching solution. .

Bump electrodes can be formed through such steps.

However, when the bump electrode is formed through the manufacturing process shown in FIG. 2 corroded and broke, so it was not always satisfactory.

Therefore, in order to prevent the etching solution from reaching the aluminum pad 2, a resin such as polyimide is coated on the cover film 3.
The formed bump electrode is, for example, disclosed in Japanese Patent Application Laid-Open No. 58-89244.
．． This was proposed in Japanese Patent Application Laid-Open No. 58-50756.

[Problem to be solved by the invention]

As mentioned above, JP-A-57-89%44, JP-A-58-5
0756 shows a bump electrode in which a polyimide resin is formed on a cover film 3 made of PSG. However, the above-mentioned known examples do not clearly show the appearance of edges after patterning the polyimide resin. The shape of the edge of the polyimide resin is important since it affects the miniaturization of the bump electrode size and the coverage of the barrier metal layer 4.

That is, as the shape of the edge of the polyimide resin, for example, structures shown in FIGS. 3(a) and 3(b) can be considered.

FIG. 3 (al indicates that the edge of the polyimide layer 8 is the cover film 3)
The figure shows an example in which it is formed on the outside.

In addition, FIG. 3 (bl) shows an example in which the edge of the polyimide layer 8 is on the edge of the cover film 3. In the case of an edge shape as shown in FIG. Therefore, when the barrier metal layer 4 is subsequently sputtered by a sputtering method onto the polyimide layer 8 including the contact window portion, the coverage of the barrier metal layer at the contact window portion becomes poor.

(See Figures 3(b) and b) If the coverage is poor in this way, the barrier metal layer 4 may be disconnected, and the aluminum pad 2 and gold bump 5 may react at this disconnection, producing products with high resistance. There is a possibility that the plating electrode cannot be removed and the gold bumps 5 cannot be formed sufficiently.Also, for the polyimide layer 8, after applying polyimide to the entire surface, a resist layer is formed on the polyimide, and the resist layer is formed using photolithography technology. Although it is formed by opening a window in the layer and performing etching using this as a mask, it is difficult to form the edge of the polyimide layer 8 on the edge of the cover film 3 with good reproducibility due to the alignment margin of the resist. It is.

FIG. 4 shows a cross-sectional view of the process for forming an edge shape as shown in FIG. 3 (al). As shown in FIG. The polyimide film thickness differs between the upper and lower parts, for example, dl and ax.
When etching the polyimide using the resist layer 9 as a mask, the portion of the film K dt must be completely etched, which increases the etching time and increases the amount of side etching to the region below the resist layer 9. .

Therefore, the length of part a in Fig. 3(a) becomes longer,
The portion of the cover film 3 shown in C, where it is difficult to miniaturize the size of the gold bumps 5, is exposed from the polyimide layer 8. If there is an exposed portion of the cover film 3 in this way, there is a risk of cranking if there is a thermal change in the bump electrode, such as when a lead is thermocompression bonded to the gold bump 5. Particularly, the portion indicated by C above is connected to the gold bump 5 via the barrier metal layer 4, and there are many occurrences of blank cranks in other regions.

An object of the present invention is to provide a method for manufacturing an edge shape of a polyimide resin layer that improves poor coverage of a barrier metal layer, enables miniaturization of bump electrodes, and prevents the occurrence of cranks in the cover film. do.

[Means for solving problems]

In view of the above problems, the present invention solves the above problems by inserting an edge of the polyimide layer within the contact window on the aluminum pad 2.

That is, the present invention includes the steps of: covering a semiconductor substrate on which a metal pad is formed in a predetermined region of the surface with a cover film, and then forming a first contact window on a predetermined region of the metal pad; forming a polyimide resin layer on the cover film including the inside of the contact window, and then forming a second contact window inside the first contact window; The method is characterized by comprising the steps of forming a barrier metal layer on the barrier metal layer, forming metal bumps in predetermined areas on the barrier metal layer, and etching the barrier metal layer using the metal bumps as a mask. .

[For production]

According to the present invention, the etching of the polyimide layer is performed as shown in FIG.
As shown in b), since only the portion with the film thickness d3 is etched, the film thicknesses dl+ and d! are the same as in the conventional method. The controllability of etching is improved compared to the case where both of the two are etched (see FIG. 4). Also, d.

<d, so the amount of side etching is also smaller than in the conventional case. Furthermore, even if side etching is performed, if this side etching remains within the contact window,
The size of the bump electrode is not affected by this side etching, making it easy to miniaturize the bump electrode.

Furthermore, since the contact window portion on the aluminum pad has a stepped shape, the coverage of the polyimide layer within the contact window is improved.

Furthermore, since the cover film is completely surrounded by the polyimide layer, it is possible to prevent cranking of the cover film due to thermal stress applied to the bump electrodes.

〔Example〕

FIG. 1 shows a cross-sectional view of the manufacturing process of a bump electrode to explain the present invention. Embodiments of the present invention will be described below with reference to FIG.

As shown in FIG. 1 (al), a PSG layer 10 of about 0.7 μm is deposited on a semiconductor substrate including an aluminum pad 2 by a method such as chemical vapor deposition, and then a silicon nitride layer 11 is deposited with a thickness of about 0.3 μm.
form m. The silicon nitride layer 11 is provided to improve the moisture resistance of the cover film. Next, a window is opened on the aluminum pad 2 using photolithography technology,
forming a first contact window;

Next, as shown in FIG. 1 (bl), polyimide is applied to the entire surface to form a polyimide layer 8 with a thickness of about 1 to 2 μm, and then a second contact window is formed in the first contact window using a photography technique. A contact window is formed. Through this process, the polyimide layer 8 extends to the top of the aluminum pad 2. The etching method for the polyimide layer 8 is to apply a resist to the entire surface and open a window in the contact window area. Later, the polyimide was removed using hydrazine at 30°C. A positive resist was applied to the entire surface, the contact window was exposed, and then the resist layer in the exposed area was peeled off using a developer, and at the same time, the polyimide layer immediately below it was also removed. There are ways to do this.

Next, as shown in FIG. 1C, after the polyimide layer 8 is betatized, a barrier metal layer 4 is formed on the entire surface by a method such as sputtering. This barrier metal layer 4 is, for example, 2
It has a layered structure, and the lower layer metal uses titanium, titanium nitride/chromium, and the upper layer metal uses noble metals such as palladium, platinum, and gold. The lower metal layer is provided mainly to prevent reaction between the aluminum pad 2 and the gold bumps that will be formed later, and the upper metal layer is provided mainly to improve adhesion with the gold bumps. Next, a thick resist layer 6 having a thickness of about 15 to 30 μm is formed on the barrier metal N4, and a window is opened in the gold bump formation region.

Next, as shown in FIG. 1<d), electroplating is performed using the barrier metal layer 4 as a plating electrode to form gold bumps 5 having a thickness of about 25 μm. Finally, after peeling off the resist layer 6, the barrier metal layer 4 is removed using the gold bumps 5 as a mask.
etching.

As the etching solution, a known one based on hydrogen regia and hydrofluoric acid is used. Through these steps, a bump electrode can be completed.

〔Effect of the invention〕

According to the present invention (because the edge of the polyimide layer is extended to the top of the aluminum pad, the coverage of the finer ametal layer 4 is improved.Furthermore, since the cover film is completely covered with the polyimide layer, the cover film This can prevent the occurrence of cranks.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the manufacturing process of a bump electrode explaining the present invention, Fig. 2 is a sectional view of the manufacturing process of a conventional bump electrode, and Fig. 3 is a sectional view of the bump electrode showing the edge shape of a conventional polyimide resin. FIG. 4 shows cross-sectional views of a semiconductor device showing a conventional patterning process of polyimide resin. Further, 1 is a semiconductor substrate, 2 is an aluminum pad, 3 is a cover film, 4 is a barrier metal layer, and 5 is a gold bump. 6 and 9 are resist layers, 7 is a contact window, 8 is a polyimide layer, 10 is a PSG layer, and 11 is a SIN layer, respectively. He/Yabo Toen 〆ゝ\l 、（Nara 4 Akira
[Tenmen old]' Figure 2

Claims (1)

[Claims] In a method of manufacturing a bump electrode formed on a semiconductor chip, a semiconductor substrate on which metal pads are formed on a predetermined region of the surface is covered with a cover film, and then a bump electrode is formed on a predetermined region of the metal pad. forming a polyimide resin layer on the cover film including the inside of the first contact window, and then forming a second contact window inside the first contact window. forming a barrier metal layer on the polyimide resin layer including the inside of the second contact window; forming metal bumps in predetermined areas on the barrier metal layer; and using the metal bumps as a mask. A method for manufacturing a semiconductor device, comprising the step of etching the barrier metal layer.