JPH06163547A - Semiconductor device - Google Patents

Abstract

PURPOSE:To enhance bonding strength between bump and lead terminal by forming an underlying electrode pad having same size as an opening in a substrate and same thickness as a surface protective film directly below the opening of the substrate. CONSTITUTION:An underlying electrode pad 7 having substantially same size as an opening 3a and substantially same thickness as a surface protective film 3 is provided on a semiconductor substrate 1 directly below the opening 3a of the surface protective film 3. An electrode pad 2 to be formed while covering the underlying electrode pad 7 is provided with a protrusion 2a having substantially same size as the underlying electrode pad 7 and a height substantially same as the thickness of the surface protective film 3. The surface protective film 3 is formed such that the opening 3a is located at that part thus eliminating level difference. This constitution enhances bonding strength between bump and lead terminal and prevents fracture by avoiding local concentration of mechanical or thermal stress functioning on the underlying metal film of bump. Similar effect can be achieved by forming an annular groove having inner diameter equal to the outer diameter of the opening part and depth equal to the thickness of surface protective film in the semiconductor substrate directly below the opening part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having bumps.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view showing a structure near a bump used in a conventional semiconductor device. In the figure, 1 is a semiconductor substrate on which an integrated circuit (not shown) is formed, and 2 is a semiconductor substrate. Electrode pads 3, which are formed on the semiconductor substrate 1 and serve as input / output terminals of the integrated circuit, are formed so as to cover the semiconductor substrate 1 and the electrode pads 2, and have an opening 3a for exposing the central portion of the electrode pad 2. The surface protection film 4 which it has is formed on the electrode pad 2 and the surface protection film 3 so as to completely cover the opening 3a, and the bump base metal film 5 serving as a barrier metal is formed via the bump base metal film 4. The bumps are bump electrodes.

As shown in this figure, the bump base metal film 4 is formed.
Is a shape having a concave portion that reflects a step due to the opening 3 a of the surface protective film 3. Furthermore, since the lower surface of the bump 5 reflects the surface shape of the bump underlying metal film 4 and has a convex portion in the center, the upper surface of the bump 5 has a concave portion 5a in the center. That is, the surface protective film 3 has the opening 3a.
Therefore, the upper surface of the bump 5 has a surface shape having the concave portion 5a.

When mounting the semiconductor device having the above structure by a film carrier method, which is one of the methods for packaging, the electrode pad 2 and the lead terminal 6 of the film carrier are separated from each other as shown in FIG. , And is bonded via the bumps 5 formed on the electrode pads 2. However, since the recess 5a exists on the upper surface of the bump 5 as described above, a gap is formed in the center, and the bump 5 is connected to the lead terminal 6 only at the peripheral portion.

[0005]

The conventional semiconductor device is
With the above-described structure, the bump 5 and the lead wire terminal 6 are bonded to each other in the peripheral portion of the bump 5, and the bonding strength between the bump 5 and the lead terminal 6 is reduced. Further, since mechanical stress and heat exerted on the bump 5 from the lead terminal 6 when connecting the lead terminal 6 to the bump 5 are given only through the peripheral portion of the bump 5,
Mechanical stress and thermal stress acting on the bump underlying metal film 4 and the like via the bumps 5 are locally concentrated on the peripheral portion of the lower surface of the bumps 5. Therefore, there is a problem that the semiconductor substrate 1, the electrode pad 2, the surface protective film 3, and the bump underlying metal film 4 are destroyed by the stress concentration.

The present invention has been made in order to solve the above problems, and it is possible to increase the bonding strength between the bump and the lead terminal, and at the same time, the mechanical stress acting on the bump underlying metal film or the like from the lower surface of the bump. Further, by avoiding local concentration of thermal stress, it is an object to obtain a highly reliable semiconductor device in which a bump underlying metal film or the like is not destroyed.

[0007]

According to a first aspect of the present invention, there is provided a semiconductor device having the same size as the opening and the same thickness as the surface protective film on the semiconductor substrate immediately below the opening. The electrode pad base is formed.

A semiconductor device according to claim 2 of the present invention is
An annular groove is formed in the semiconductor substrate immediately below the opening, the inner diameter of the groove is the same as the outer diameter of the opening, and the depth of the groove is the same as the thickness of the surface protective film.

[0009]

In the semiconductor device according to the first aspect of the present invention, the electrode pad base is provided on the semiconductor substrate having the same size as the opening and the same thickness as the surface protection film and directly below the opening. Therefore, when the surface protective film is formed, no step is formed between the upper surface of the electrode pad and the upper surface of the surface protective film.

In the semiconductor device according to the second aspect of the present invention, by providing the semiconductor substrate with a groove having a predetermined size, no step is formed between the upper surface of the electrode pad and the upper surface of the surface protective film. .

[0011]

【Example】

Example 1. The first embodiment is an embodiment according to claim 1 of the present invention. 1 is a cross-sectional view showing a first embodiment of the present invention. In the figure, the same or corresponding parts as those of the conventional semiconductor device shown in FIGS. 4 and 5 are designated by the same reference numerals, and the description thereof will be omitted. Reference numeral 7 denotes an electrode pad base formed on the semiconductor substrate 1 directly below the opening 3a of the surface protection film 3 and having a size substantially the same as the opening 3a and a thickness substantially the same as the surface protection film 3. .

In this way, the electrode pad base 7 is provided,
By setting the size and thickness as described above, the electrode pad 2 formed to cover the electrode pad base 7 is formed.
Is formed with a protrusion 2a having substantially the same size as the electrode pad base 7 and the same height as the thickness of the surface protective film 3. Further, if the surface protection film 3 is formed so that the opening 3a is located at the protruding portion 2a, as described above, the protruding portion 2a is formed.
Since the height of the surface protection film 3 and the thickness of the surface protection film 3 are substantially the same, no step is formed between the upper surface of the surface protection film 3 and the upper surface of the protrusion 2a of the electrode pad 2.

Further, as shown in FIG. 2, the surface protective film 3
If the bump underlying metal film 4 is formed on the surface of the bump protective layer 3, the upper surface of the surface protective film 3 is naturally flat without steps, and the lower surface of the bump 5 formed on the surface protective film 3 is also flat. . Therefore, the upper surface of the bump 5 is also formed flat without any unevenness. When the lead terminals 6 are joined onto the bumps 5, the lead terminals 6 are entirely connected to the upper surfaces of the bumps 5, so that mechanical stress and thermal stress are locally concentrated as in the conventional case. There is no fear.

Regarding the formation of the electrode pad base 7, if the electrode pad base 7 is formed using SiO ₂ or polycrystalline Si which is generally used in the step of forming an integrated circuit on the semiconductor substrate 1, The electrode pad base 7 can be easily formed without adding a special step for forming 7.

Example 2. The second embodiment is an embodiment according to claim 2 of the present invention. In the first embodiment, the electrode pad base 7 is provided to prevent a step from occurring between the upper surface of the electrode pad 2 and the upper surface of the surface protective film 3. However, in the second embodiment, as shown in FIG. By forming the doughnut-shaped groove 1a in the semiconductor substrate 1, a step is not generated between the upper surface of the electrode pad 2 and the upper surface of the surface protective film 3. In this case, the inner diameter of the groove 1a is substantially the same as the size of the opening 3a of the surface protective film 3, and the depth of the groove 1a is substantially the same as the thickness of the surface protective film 3.

With this structure, the projection 2 is formed on the electrode pad 2.
As a result, the height of the protrusion 2a becomes substantially the same as the depth of the groove 1a. Since the depth of the groove 1a is substantially the same as the thickness of the surface protective film 3, the height of the protrusion 2a is substantially the same as the thickness of the surface protective film 3. Therefore, no step is formed between the upper surface of the surface protective film 3 and the upper surface of the protrusion 2a of the electrode pad 2, and the same effect as that of the above-described first embodiment is obtained.

[0017]

Since the present invention is constructed as described above, it has the following effects.

According to the semiconductor device of the first aspect of the present invention, the electrode pad base having the same size as the opening and the same thickness as the surface protection film is formed immediately below the opening on the semiconductor substrate. Therefore, there is an effect that the bonding strength between the bump and the lead terminal can be increased, and the bump underlying metal film or the like is not broken, and the reliability is increased.

According to the semiconductor device of the second aspect of the present invention, the annular groove is formed on the semiconductor substrate immediately below the opening, and the inner diameter of the groove is the same as the outer diameter of the opening. Since the depth is the same as the thickness of the surface protective film, the same effect as in claim 1 can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state before forming bumps according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing Embodiment 1 of the present invention.

FIG. 3 is a cross-sectional view showing a state before forming bumps according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a structure near a bump used in a conventional semiconductor device.

FIG. 5 is a cross-sectional view showing a state in which a bump and a lead terminal are joined in a conventional semiconductor device.

[Explanation of symbols]

 1 Semiconductor Substrate 1a Groove 2 Electrode Pad 3 Surface Protection Film 3a Opening 5 Bump 7 Electrode Pad Base

Claims (2)

[Claims] 1. A semiconductor substrate on which an integrated circuit is formed, an electrode pad formed on the semiconductor substrate and electrically connected to the integrated circuit, and formed so as to cover the semiconductor substrate and the electrode pad. A semiconductor device having a surface protection film having an opening on the electrode pad, and a bump formed to completely cover the opening and connecting an input / output signal of the integrated circuit to the outside. 2. The semiconductor device according to claim 1, wherein an electrode pad base having the same size as the opening and the same thickness as the surface protective film is formed on the semiconductor substrate directly below the opening. 2. A semiconductor substrate on which an integrated circuit is formed, an electrode pad formed on the semiconductor substrate and electrically connected to the integrated circuit, and formed so as to cover the semiconductor substrate and the electrode pad. A semiconductor device having a surface protection film having an opening on the electrode pad, and a bump formed to completely cover the opening and connecting an input / output signal of the integrated circuit to the outside. In, an annular groove is formed on the semiconductor substrate at a position directly below the opening, the inner diameter of the groove is the same as the outer diameter of the opening, and the depth of the groove is the thickness of the surface protective film. And a semiconductor device which is the same as the semiconductor device.