JPH11145199A - Semiconductor device - Google Patents

Abstract

(57) Abstract: The present invention relates to a semiconductor device having a projecting electrode (bump) as an external connection terminal, and an object thereof is to enable highly reliable flip chip mounting. In a semiconductor device having a structure in which a plurality of pads are formed on a chip body and bumps are disposed on the pads, the bumps are formed into an oval shape to form an oval bump. Then, the rectangular pad 38 is formed by making the shape of the pad rectangular. Then, the elliptical bump 36 is arranged on the rectangular pad 38 such that the longitudinal direction of the elliptical bump 36 matches the longitudinal direction of the rectangular pad 38.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device,
In particular, the present invention relates to a semiconductor device having a protruding electrode (bump) as an external connection terminal. In recent years, the density and miniaturization of semiconductor devices have been rapidly progressing, and the number of external connection terminals provided in the semiconductor device has increased accordingly, and the pitch between external connection terminals has been reduced. Tend to.

For this reason, a mounting structure has been proposed and implemented in which a bump (protruding electrode) is provided as an external connection terminal of a semiconductor device and this is flip-chip mounted on a mounting substrate.

[0003]

2. Description of the Related Art FIG. 8 shows a state in which a conventional semiconductor device 8 (in the following description, an example using a semiconductor chip as a semiconductor device) is flip-chip mounted on a mounting substrate 2. The mounting substrate 2 has a wiring 6 formed in a predetermined pattern on the upper surface of a resin or ceramic substrate main body 4. Further, as shown in FIG. 9, the semiconductor chip 8 is provided with a plurality of bumps 10 (shown in satin) serving as projecting electrodes on the circuit forming surface 14 of the chip body 12 (substrate).

The bump 10 is a stud bump and is formed by using a wire bonding technique. The bump 10 has a shape having a lower portion 10a and an upper portion 10b. In particular, the lower portion 10a has a substantially hemispherical shape. As described above, the bumps 10 are provided on the circuit forming surface 14 of the chip body 12, and the pads 16 are formed at the bump forming positions of the chip body 12. Therefore,
The bump 10 is joined to the pad 16, so that the bump 10 is joined to the chip body 12.

As shown in FIG. 9, the pad 16 has a circular shape in plan view corresponding to the shape of the bump 10 (ie, the substantially hemispherical shape of the lower portion 10a). As described above, the pad 16 is connected to the bump 1
0 is to be joined, so that the diameter W1 of the pad 16 is set to be larger than the diameter R1 of the bump 10 in consideration of a positioning error, a mounting error, and the like (W1).
> R1).

The semiconductor chip 8 having the above configuration is flip-chip mounted on the mounting substrate 2. In this mounted state, the bumps 10 are fixed to the wiring 6 by a conductive adhesive 26. Thus, the semiconductor chip 8 is electrically and mechanically connected to the flip-chip mounting substrate 2. By the way, in the related art where the density of the semiconductor chip 8 has not been increased as recently,
And the pitch P1 between the adjacent pads 16 could be widened.

Therefore, the area of each pad 16 (diameter W1)
And the shape (diameter dimension R1) of the bump 10 could be increased accordingly. For this reason,
Bump 1 when bump 10 is bonded to pad 16
The bonding area between the pad 0 and the pad 16 can be made large, so that a bonding with high bonding strength and high reliability can be performed.

[0008]

However, with the recent rapid increase in the density and miniaturization of semiconductor chips, the number of pins provided on the semiconductor chip tends to increase. FIG.
Shows a conventional semiconductor chip 18 in which the number of pins is increased with respect to the semiconductor chip 8 shown in FIG. As described above, when the size of the semiconductor chip 18 is reduced and the number of pins is increased, the adjacent pitch P2 of the pads 22 provided on the chip body 12 becomes the pitch between the pads 16 of the semiconductor chip 8 shown in FIG. Inevitably narrower than P1 (P2 <
P2).

Further, since the interference between the adjacent pads 22 is not allowed, the area (diameter W2) of each pad 22 is reduced by reducing the pitch P2 between the pads as described above.
Is also smaller. Further, as the area (diameter W2) of each pad 22 becomes smaller, the shape (diameter dimension R2) of the bump 20 must be reduced. For this reason, in the semiconductor chip 18 shown in FIG. 10, when the bump 20 is bonded to the pad 22, the bonding area between the bump 20 and the pad 22 is reduced, and the bonding force between the bump 20 and the pad 22 is reduced. I will. Therefore, there is a problem that the semiconductor chip 18 is easily detached from the mounting substrate 2 and the reliability of flip-chip mounting is reduced.

The present invention has been made in view of the above points, and has as its object to provide a semiconductor device which enables highly reliable flip-chip mounting.

[0011]

Means for Solving the Problems In order to solve the above problems, the present invention is characterized by taking the following means. According to the first aspect of the present invention, in the semiconductor device having a plurality of protruding electrodes, the protruding electrodes are formed in an elliptical shape, and the protruding electrodes are arranged in rows so that the longitudinal directions thereof are parallel to each other. It is a feature.

According to a second aspect of the present invention, in the semiconductor device having a plurality of pads and a bump electrode provided on the pad, the bump electrode has an elliptical shape and the pad has an elliptical shape. Is formed in a rectangular shape, and the protruding electrodes are arranged on the pad such that the longitudinal direction of the pad coincides with the longitudinal direction of the protruding electrode.

Each of the above means operates as follows. According to the first aspect of the present invention, the shape of the protruding electrodes is an elliptical shape, and the protruding electrodes are arranged so that the longitudinal directions of the protruding electrodes are parallel to each other. This makes it possible to arrange the protruding electrodes with high density. Accordingly, it is possible to easily cope with the miniaturization and the increase in the number of pins of the semiconductor device.

According to the second aspect of the present invention, the shape of the protruding electrode is made elliptical, the shape of the pad is made rectangular, and the longitudinal direction of the pad coincides with the longitudinal direction of the protruding electrode. By arranging the protruding electrodes on the pads, it is possible to arrange adjacent protruding electrodes in close proximity, and it is possible to arrange the protruding electrodes with high density.

Further, since the protruding electrodes can be formed longer in the longitudinal direction, even if the distance between the adjacent protruding electrodes is shortened as described above, the bonding area between the protruding electrodes and the pad is reduced. It can be widened, and thus the bonding strength between the protruding electrode and the pad can be kept large.

[0016]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partially enlarged view of a semiconductor device according to an embodiment of the present invention (an example in which a semiconductor chip 30 is used as a semiconductor device will be described below). FIG. This shows a state where flip-chip mounting is performed on the substrate 46.

The semiconductor chip 30 is a so-called bare chip. A predetermined circuit is formed on a circuit forming surface 34 of a chip body 34 (substrate) made of, for example, silicon or gallium-arsenic, and surrounds a circuit forming portion. A plurality of pads 38 are formed. The present embodiment is characterized in that the shape of the pad 38 is rectangular (that is, rectangular). Hereinafter, the rectangular pad 38 is referred to as a rectangular pad 38.

The size of the pad 38 is the length W of the short side.
S (short stitch length) is approximately equal to the pad diameter W2 of the high-density semiconductor chip 18 described above with reference to FIG. 10 (WS ≒ W2). On the other hand, the long side length WL
(Long side length) is set to be longer than the pad diameter W2 of the semiconductor chip 18 (WL> W2). As shown in FIG. 1, the pads 38 are arranged so that their longitudinal directions are parallel to each other. In other words, adjacent pads 38 are arranged in a row such that their long sides face each other in parallel.

By arranging the pads 38 in this manner, the pads 3 are arranged in the directions indicated by arrows X and Y in FIG.
When the rows 8 are arranged, the pads 38 can be arranged at a high density (that is, a large number of pads 38 can be arranged within a unit length). As a result, even if the semiconductor chip 30 has a higher density and a higher number of pins, it is possible to easily cope with this.

Next, the bump 36 (protruding electrode) provided on the pad 38 having the above-described configuration will be described with reference to FIGS. 2 to 5 in addition to FIG. In this embodiment, the bump 3
A stud bump is adopted as 6 and is formed in a substantially elliptical shape when the shape is viewed in a plan view (hereinafter, this bump 36 is referred to as an elliptical bump 36). That is, as shown in FIGS. 1 to 3, the elliptical bump 36 has different diameters in the longitudinal direction and the direction perpendicular thereto, and specifically has a major diameter RL and a minor diameter RS. (RL> RS).

The oval-shaped bump 36 is connected to the lower portion 36.
a and an upper portion 36b, the lower portion 36a has a substantially elliptical shape as described above, and the upper portion 36b projecting above the upper portion has a substantially cylindrical shape.
That is, the elliptical bump 36 according to the present embodiment has a so-called two-stage bump shape. The elliptical bump 36 is provided on the circuit forming surface 34 of the chip body 32, and a rectangular pad 38 having the above-described rectangular shape is formed at a predetermined bump forming position on the circuit forming surface 34. ing. Therefore, as shown in FIG.
When 0 is flip-chip mounted on the mounting substrate 46, the elliptical bumps 36 are bonded to the respective rectangular pads 38, whereby the semiconductor chip 30 and the mounting substrate 46 are electrically connected.

At the time of flip-chip mounting, the elliptical bump 36 is fixed to the wiring 6 by an adhesive 49 having conductivity. As described above, the elliptical bump 36 has a two-stage shape having the lower portion 36a and the upper portion 36b.
Can be electrically and mechanically connected to the mounting substrate 46. Also, the semiconductor chip 3 can be used without using solder.
Since 0 can be mounted on the mounting substrate 46, it is possible to comply with the lead regulation.

The following description focuses on the bonding structure between the elliptical bump 36 and the rectangular pad 38. First, focusing on the sizes of the oval bump 36 and the rectangular pad 38, in this embodiment, the major axis RL of the oval bump 36 is set to be slightly smaller than the major side length WL of the rectangular pad 38. Cage (RL <WL), similarly oval bump 36
Is set slightly smaller than the short side length WS of the rectangular pad 38 (RS <WS).

With this configuration, when the semiconductor chip 30 is flip-chip mounted on the mounting substrate 46, the semiconductor chip 30 is reliably mounted on the mounting substrate 46 even if there are positioning errors and mounting errors. It becomes possible. Next, attention is paid to the bonding direction of the elliptical bump 36 to the rectangular pad 38. As described above, the rectangular pad 38 has a rectangular shape, and the oval bump 36 has an oval shape. When joining the elliptical bump 36 to the rectangular pad 38, the elliptical bump 36 is joined so that the longitudinal direction of the elliptical bump 36 matches the longitudinal direction of the rectangular pad 38.

By bonding the elliptical bumps 36 to the rectangular pads 38 in this manner, adjacent elliptical bumps 36 can be arranged close to each other (that is, the pitch between the bumps can be reduced. Therefore, the elliptical bumps 36 can be arranged at a high density. Therefore, even if the semiconductor chip 30 has a higher density and a higher number of pins, it can sufficiently cope with this.

In order to cope with the increase in the density and the number of pins of the semiconductor chip 30 as described above, a direction perpendicular to the longitudinal direction (ie, a direction indicated by arrows X and Y in FIG. 1). It is important to dispose the oval bumps 36 and the rectangular pads 38 at a narrow pitch. On the other hand, in the longitudinal direction, since this does not directly affect the increase in the density and the number of pins of the semiconductor chip 30, it is necessary to form the oval bumps 36 and the rectangular pads 38 long in the longitudinal direction. It is possible. That is, even if the long diameter RL of the oval-shaped bump 36 and the long side length WL of the rectangular pad 38 are made long, the increase in the density and the number of pins of the semiconductor chip 30 are not hindered.

For this reason, in this embodiment, the semiconductor chip 30
The long diameter RL of the elliptical bump 36 and the long side length WL of the rectangular pad 38 are formed as long as possible without hindering the miniaturization of the device. With this configuration, it is possible to increase the bonding area between the elliptical bump 36 and the rectangular pad 38 when the semiconductor chip 30 is mounted on the mounting substrate 46.

As is well known, the bonding strength between the bump and the pad increases as the bonding area between the bump and the pad increases. Even if the pitch P3 is reduced, the bonding force between the elliptical bump 36 and the rectangular pad 38 can be maintained large, and the reliability of flip chip mounting can be improved.

Next, a method of forming the above-mentioned elliptical bump 36 will be described with reference to FIGS. As described above, the elliptical bump 36 used in this embodiment is used.
Is a stud bump. As is well known, stud bumps are generally formed using a wire bonding technique. The elliptical bump 36 in the present embodiment can also be formed by using a wire bonding technique, similarly to the commonly used stud bump.

Hereinafter, a specific method of forming the oval bump 36 will be described. In order to form the elliptical bump 36 by the wire bonding technique, first, a capillary 40 provided in a wire bonding apparatus is pressed against a rectangular pad 38, and a wire (gold wire) 42 inserted inside is formed.
Is ultrasonically welded to the rectangular pad 38. At this time, in this embodiment, the lower cavity portion 44a and the upper cavity portion 44b are formed in advance in the capillary 40 used. The lower cavity portion 44a is a concave portion having a substantially semi-elliptical spherical shape, and its major axis and minor axis are set to correspond to the major axis RL and minor axis RS of the above-described elliptical bump 36. The upper cavity portion 44b has a cylindrical shape corresponding to the shape of the upper portion 36b of the oval bump 36.

Therefore, the capillary 40 is connected to the rectangular pad 3
The elliptical bump 36 shown in FIGS. 2 and 3 is automatically formed by ultrasonically welding the gold wire 42 to the rectangular pad 38 at 8. That is, the capillary for wire bonding provided in the wire bonding apparatus generally used in the related art is simply replaced with the capillary 40 shown in FIGS. Can be formed.

As a result, the elliptical bump 36 can be formed at a high throughput without largely changing the semiconductor manufacturing equipment, and the cost of the manufactured semiconductor chip 30 can be reduced. Next, FIG.
A modification of the semiconductor chip 30 described with reference to FIG. 6 will be described.

FIG. 7 shows a semiconductor chip 50 which is a modification of the semiconductor chip 30 described above. Note that FIG.
In FIG. 6, the same components as those of the semiconductor chip 30 described with reference to FIGS. The present modification is characterized in that the longitudinal direction of each of the elliptical pad 52 and the rectangular pad 54 provided on the chip main body 32 is radially oriented with respect to the center position of the chip main body 32. Things.
With this configuration, the reliability when the semiconductor chip 50 is mounted on the mounting substrate can be improved.
Hereinafter, the reason will be described.

The semiconductor chip 30 thermally expands when heated. At this time, the chip body 32 expands radially as indicated by arrows in FIG. Therefore, when the heat treatment is performed after the semiconductor chip 30 is mounted on the mounting substrate, a stress is also applied to each oval pad 52 in the radial direction with respect to the center of the chip body 32. Here, considering the peel strength of the oval pad 52, the peel strength of the oval pad 52 in the longitudinal direction (the direction indicated by the arrow A in FIG. 7) is orthogonal to the longitudinal direction of the oval pad 52. (The direction indicated by arrow B in FIG. 7).

Therefore, as in this modification, the chip body 32
Oval pad 52 and rectangular pad 54 disposed on
Are arranged so that the respective longitudinal directions thereof are directed radially with respect to the center position of the chip main body 32. Since the peeling strength of the oval pad 52 is large, the semiconductor chip 30
Can be prevented from separating from the mounting substrate. Therefore, by adopting the configuration of the present modified example, it is possible to improve the reliability when the semiconductor chip 50 is mounted on the mounting substrate.

In the above-described embodiment, the semiconductor devices 30 and 50 in a bare chip state have been described as examples of the semiconductor device. However, the application of the present invention is not limited to this. It can be widely applied to semiconductor devices having bumps (protruding electrodes) such as a Grid Array. Further, in the above-described embodiment, the method in which the oval bumps 36 and 52 are formed as stud bumps using the wire bonding technique has been described as an example. However, the oval bumps are not limited to the stud bumps. Instead, bumps having other configurations such as solder bumps can be used. Also, as the manufacturing method, various bump forming methods such as a plating method and a transfer method can be used.

[0037]

According to the present invention as described above, the following various effects can be realized. According to the first aspect of the present invention, it is possible to dispose the adjacent protruding electrodes in close proximity, and to arrange the protruding electrodes at a high density. Can be handled.

Further, according to the second aspect of the present invention, it is possible to arrange the adjacent protruding electrodes close to each other, and it is possible to arrange the protruding electrodes at a high density. Further, since the protruding electrode can be formed longer in the longitudinal direction, the bonding area between the protruding electrode and the pad can be increased even if the distance between the adjacent protruding electrodes is shortened. The bonding strength between the electrode and the pad can be kept large.

[Brief description of the drawings]

FIG. 1 is an enlarged view showing a bottom surface of a semiconductor chip according to an embodiment of the present invention.

FIG. 2 is a front view of an elliptical bump provided on a semiconductor chip according to one embodiment of the present invention.

FIG. 3 is a side view of an elliptical bump provided on a semiconductor chip according to one embodiment of the present invention.

FIG. 4 is a cross-sectional view of a capillary used when forming an elliptical bump provided on a semiconductor chip according to one embodiment of the present invention.

FIG. 5 is a longitudinal sectional view of a capillary used when forming an elliptical bump provided on a semiconductor chip according to one embodiment of the present invention.

FIG. 6 is a diagram showing a state in which a semiconductor chip according to one embodiment of the present invention is flip-chip mounted on a mounting substrate.

FIG. 7 is a diagram showing a bottom surface of a semiconductor chip which is a modification of the present invention.

FIG. 8 is a view showing a state in which a semiconductor chip as an example of the related art is flip-chip mounted on a mounting substrate.

FIG. 9 is an enlarged view of a bottom surface of a semiconductor chip as an example of the related art (part 1).

FIG. 10 is an enlarged view showing a bottom surface of a semiconductor chip as an example of the related art (part 2).

[Explanation of symbols]

 30, 50 Semiconductor chip 32 Chip main body 36, 52 Elliptical bump 38, 54 Rectangular pad 40 Capillary 42 Gold wire 44 Cavity 46 Mounting substrate 47 Substrate main body 48 Wiring

Claims (2)

[Claims] 1. A semiconductor device having a plurality of protruding electrodes, wherein the protruding electrodes have an elliptical shape, and the protruding electrodes are arranged in rows so that the longitudinal directions thereof are parallel to each other. Semiconductor device. 2. A semiconductor device having a plurality of pads and a projection electrode disposed on the pad, wherein the projection electrode has an elliptical shape, the pad has a rectangular shape, and A semiconductor device, wherein the protruding electrode is disposed on the pad such that a longitudinal direction of the pad coincides with a longitudinal direction of the protruding electrode.