JPH10112514A - Semiconductor device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the dislocation of solder balls and shorting between the solder balls at the time of mounting the solder balls of BGA(ball grid array) and the like. SOLUTION: Holes 7 for solder ball mounting and the hollow part of the metal pad are provided in the metal pad for solder ball mounting 4, and a solder paste film 5 is formed at the periphery. Then, solder balls 6 are mounted. Thus, the dislocation of the solder balls can be prevented, and the solder balls can be installed stably. Consequently, a BGA device which is mechanically shock-proof from the outside can be manufactured, by melting and solidifying (5A) the solder paste film 5 in such a state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a semiconductor device having a plurality of solder ball connection terminals such as a ball grid array (BGA). And a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, semiconductor devices have become highly integrated and highly functional, and a large number of connection terminals are required in comparison with their dimensions. On the other hand, in electronic devices mounted with a semiconductor device, miniaturization of the device is rapidly progressing, and miniaturization of a semiconductor device to be used is required.

[0003] Against this background, QFP (Quad
In semiconductor devices of the Flat Package) type, the distance between terminals has been rapidly reduced. However, with the reduction in the terminal spacing, for example, when soldering a semiconductor device, adjacent terminals come into contact with each other and become electrically conductive, causing inconveniences such as failure, and inconvenience such as an increase in assembly failure. Has been invited.

In order to solve this problem, a large number of solder balls are arranged on the bottom surface of the semiconductor device at a predetermined interval or more, and each of the solder balls is connected to the inside of the semiconductor device via wiring inside the mounting board. For example, a BGA-type semiconductor device that conducts with a semiconductor pellet has been developed.

An outline of a conventional BGA type semiconductor device will be described below with reference to FIG.

FIG. 10A is a bottom view of a BGA type semiconductor device, and FIG. 10B is a cross-sectional view taken along a dashed-dotted line XY of FIG. 10A.

In FIGS. 10 (A) and 10 (B), a semiconductor pellet 11 is mounted almost at the center of the upper surface (first surface) of the multilayer ceramic substrate 1 with its rear surface in close contact with the upper surface of the multilayer ceramic substrate 1. ing. Further, a semiconductor pellet electrode 21 is arranged in a peripheral portion of the surface of the semiconductor pellet 11. On the other hand, a substrate upper surface electrode 13 is arranged on the upper surface of the multilayer ceramic substrate 1 so as to be separated from the semiconductor pellet 11 mounting portion. One end of the bonding wire 12 is connected to the semiconductor pellet electrode 21, and the other end is connected to the substrate upper surface electrode 13 on the multilayer ceramic substrate 1. The semiconductor pellet electrode 21 and the substrate upper surface electrode 13 are electrically connected by the bonding wire 12. On the upper surface of the multilayer ceramic substrate 1, a resin cap 14 is formed with the peripheral portion fixed to the peripheral portion of the multilayer ceramic substrate 1 and hermetically sealed. The semiconductor pellet 11, the bonding wires 12, and the substrate upper surface electrode 13 is covered and protected.

On the other hand, on the back surface (second surface) of the multilayer ceramic substrate 1, a solder ball which is electrically connected to the substrate upper surface electrode 13 via the internal wiring 15 of the multilayer ceramic substrate 1 and also serves as the back surface electrode. The mounting metal pads 4 are formed in a planar shape at substantially constant intervals from each other. Solder balls 6 are mounted on the surface of the solder ball mounting metal pad 4 at a ratio of one solder ball 6 to one solder ball mounting metal pad 4. The solder ball 6 and the solder ball mounting metal pad 4 are electrically and mechanically connected by the molten and solidified solder 5A.

Next, FIG. 11 shows an example of a conventional manufacturing method in which a solder ball is mounted on a solder ball mounting metal pad 4 on the back surface of the multilayer ceramic substrate 1.

FIG. 11 (1A) to FIG. 11 (4A)
FIGS. 11 (1B) to 11 (4B) show top views of a process of mounting the solder balls 6 on the solder ball mounting metal pads 4 on the back surface of the multilayer ceramic substrate 1. FIGS.
FIGS. 11 (1A) to 11 (4A) are cross-sectional views taken along a chain line.

As shown in FIGS. 11A and 11B, a disk-shaped solder ball mounting metal pad 4 serving as a back surface electrode is formed on the back surface of the multilayer ceramic substrate 1.

Next, a solder paste film 5 is laminated on the solder ball mounting metal pad 4 by screen printing in a disk shape slightly smaller than the metal pad 4. (FIG. 11
(2A), FIG. 11 (2B)).

Thereafter, FIGS. 11 (3A) and 11 (3B)
As shown in FIG.
The solder balls 6 are mounted on the solder paste film 5. Here, since the solder paste film 5 has viscosity, the solder balls 6 are partially embedded and held in the solder paste film 5.

Subsequently, the solvent of the solder paste film 5 is volatilized and removed by heat treatment, and the solder fine particles in the solder paste film 5 are melted. After that, by cooling, FIG.
A), as shown in FIG.
The solder balls 6 can be fixed to the solder ball mounting metal pads 4 by forming the solder 5A obtained by melting and solidifying the solder 5A.

[0015]

The above-mentioned conventional semiconductor device has the following problems.

That is, as shown in FIG. 10, the solder ball 6 is merely fixed on the flat solder ball mounting metal pad 4 by the melted and solidified solder 5A. There was a problem that was weak to.

In the case of the above-mentioned conventional manufacturing method, there are the following problems.

As shown in FIGS. 11 (3A) and 11 (3B), the holding state of the solder balls 6 from the time when they are mounted on the solder paste film 5 to the time when they are subjected to the heat treatment is simply the solder paste. The film 5 is unstable only due to its viscosity. For this reason, the solder ball 6 is easily peeled off or displaced by the vibration after being mounted and before being introduced into the heating furnace. In fact, according to experiments performed by the present inventors, in the conventional manufacturing method, the number of solder balls is 200.
In the case of a ball grid array of about 250 to about 250%, a ball grid array of about 10% has a solder ball misalignment defect due to an impact during a process or the like. As a countermeasure against this misalignment, it is conceivable to increase the holding force by increasing the amount of solder paste. However, in this case, in the heating and melting step of the solder paste film 5, the molten solder paste easily causes a short circuit of the solder between adjacent substrate pads, thereby increasing the short-circuit failure rate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a semiconductor device in which a solder ball is stably fixed and which is resistant to external mechanical shock, and a solder ball formed by using an appropriate amount of solder paste. An object of the present invention is to provide a method of manufacturing a semiconductor device that can be stably mounted on a solder paste film.

[0020]

In order to solve the above-mentioned problems, in a semiconductor device according to the present invention, a mounting substrate having a first surface and a second surface opposite to the first surface is provided. A semiconductor pellet mounted on a first surface of the mounting substrate, a substrate upper surface electrode formed on a first surface of the mounting substrate and electrically connected to a semiconductor pellet electrode on the semiconductor pellet; A lower substrate electrode formed on the second surface of the substrate and electrically connected to the upper substrate electrode; and a solder ball electrically connected to the lower substrate electrode. A solder ball holding means is provided on the second surface of the substrate, the solder ball holding means being in contact with the solder ball side surface and holding the solder ball.

Further, as the solder ball holding means, a projection is provided around the solder ball on the second surface of the mounting board, the protrusion being in contact with the side surface of the solder ball.

Further, the solder ball holding means is characterized in that a portion of the second surface of the mounting board which contacts the side surface of the solder ball forms a recess.

Further, as the solder ball holding means, a metal film having a hollow portion for holding the solder ball is formed around the solder ball on the second surface of the mounting board. .

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: mounting a semiconductor pellet on a first surface of a mounting substrate; Forming solder ball holding means for contacting the solder ball side surface and holding the solder ball on the second surface on the side; forming a solder paste film around the solder ball holding means; holding the solder ball A step of fitting a part to the means, and placing a solder ball in contact with the solder paste film, a step of melting and solidifying the solder paste film, and fixing the solder ball side portion to the solder ball holding means, It is characterized by including.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a semiconductor device according to a first embodiment of the present invention will be described in detail using a BGA type semiconductor device as an example with reference to FIG.

FIG. 1 is a sectional view of a semiconductor device.

In FIG. 1, a semiconductor pellet 11 is provided substantially at the center of the upper surface (first surface) of the multilayer ceramic substrate 1.
Is mounted with its back surface in close contact with the upper surface of the multilayer ceramic substrate 1. Further, a semiconductor pellet electrode 21 is arranged in a peripheral portion of the surface of the semiconductor pellet 11. On the other hand, a substrate upper surface electrode 13 is arranged on the upper surface of the multilayer ceramic substrate 1 so as to be separated from the semiconductor pellet 11 mounting portion.
The semiconductor pellet electrode 21 has a bonding wire 12
Is connected to the substrate upper surface electrode 13 on the multilayer ceramic substrate 1. The semiconductor pellet electrode 21 and the substrate upper surface electrode 13 are electrically connected by the bonding wire 12. A resin cap 14 is provided on the upper surface of the multilayer ceramic substrate 1.
The peripheral portion is fixed to the peripheral portion of the multilayer ceramic substrate 1 and is hermetically sealed. The peripheral portion covers and protects the semiconductor pellet 11, the bonding wire 12, and the substrate upper surface electrode 13.

On the other hand, on the back (second surface) of the multilayer ceramic substrate 1A, the outermost layer 1B of the multilayer ceramic substrate having a through hole 7 acting as a solder ball holding means is formed.
Of the multilayer ceramic substrate 1A
To form the multilayer ceramic substrate 1. A solder ball mounting metal pad 4 is formed around the through hole 7 on the surface of the outermost layer 1B of the multilayer ceramic substrate. Further, an electrode film 3 as a back surface electrode is formed on the back surface of the multilayer ceramic substrate 1 </ b> A exposed from the through hole 7. The electrode film 3 is electrically connected to the substrate upper surface electrode 13 on the upper surface of the multilayer ceramic substrate 1A via the internal wiring 15 in the multilayer ceramic substrate 1A. Further, a part of the solder ball 6 is buried in the through hole 7 and is in contact with the electrode film 3.
Is placed. The solder ball 6 is connected and fixed to the solder ball mounting metal pad 4 by the molten and solidified solder 5A. Here, the solder ball 6 has a diameter of 700 microns, the through hole 7 has an inner diameter of about 500 microns, and the outermost layer 1B of the multilayer ceramic substrate has a thickness of about 100 microns.

According to the above-described semiconductor device according to the first embodiment of the present invention, the solder ball 6 has the electrode film 3 at the bottom.
Since the side portion is supported by the side edge of the through hole 7, and the upper portion is fixed thereon by the melted and solidified solder 5A, it is very stable against external force.

Further, since the position of the solder ball is stable as described above, the amount of the melted and solidified solder 5A is smaller than that in the case where the solder ball 5A is mounted on the conventional flat metal pad, and the amount of the solder ball 6A is small. Sufficient stability can be ensured. Also,
Since the amount of solder paste is sufficiently small, there is no short circuit between adjacent solder balls or metal pads for mounting solder balls.

In the above description, the electrode film 3 is the substrate upper electrode 1
3, the mounting metal pad 4 and the upper surface electrode of the substrate may be electrically connected instead.

Next, with respect to the above-described method for manufacturing a semiconductor device,
This will be described in detail with reference to FIG.

FIGS. 2A to 2A are cross-sectional views of the periphery of the solder ball mounting portion in the step of mounting the solder balls 6 in the through holes 7 on the back surface of the multilayer ceramic substrate 1 as viewed from the back surface side of the multilayer ceramic substrate 1. FIG. FIGS. 2 (1B) to 2 (5B) are cross-sectional views along XY indicated by dashed lines in FIGS. 2 (1A) to (5A).

First, a circular electrode film 3 having a thickness of about 5 μm and a diameter of about 500 μm is sintered and formed on the back surface of the multilayer ceramic substrate 1A (FIG. 2 (1A) 1, FIG. 2).
(1B) 1).

On the other hand, a metal pad 4 for mounting a solder ball having an outer diameter of about 1 mm is formed on the back surface of the outermost layer 1B of the multilayer ceramic substrate having a thickness of about 100 microns by sintering. The hole 7 is formed to have a diameter of about 500 microns (FIG. 2 (1A) 2, FIG. 2 (1B)
2).

Next, the back surface of the multilayer ceramic substrate 1A and the surface of the outermost layer 1B of the multilayer ceramic substrate are
(FIG. 2 (2)
A), FIG. 2 (2B)).

Next, a solder paste film 5 is formed on the solder ball mounting metal pad 4 by solder screen printing.
A coating is formed on the order of 0 microns.

The solder paste film 5 may be formed using a print mask (not shown) so that the solder paste film 5 is formed only on the solder ball mounting metal pad 4 (FIG. 2 (3A), FIG. 2).
(3B)).

Subsequently, a solder ball 6 having a diameter of about 700 μm is placed in the through hole 7. At this time, since the through holes 7 are formed in advance in the solder ball mounting portion, the solder balls 6 can be stably mounted in the through holes 7.
When the solder balls 6 are mounted, a large amount of the solder balls 6 are rolled on the back surface of the multilayer ceramic substrate 1 with the back surface of the multilayer ceramic substrate 1 having the through holes 7 formed thereon. Correspondingly, the solder balls 6 can be placed one by one. (FIG. 2 (4A), FIG. 2 (4
B)).

Subsequently, the solder paste film 5 is heated and melted,
By cooling and solidifying, the solder balls 6 and the solder ball mounting metal pads 4 are connected and fixed by the molten and solidified solder 5A. At this time, the melting point of the solder ball 6 is lower than the melting point of the solder forming the solder paste film, and does not melt even when the solder 5A is formed (FIG. 2 (5A), FIG. 2 (5)).
B)).

According to the manufacturing method described above, the solder balls 6
Can be stably mounted in the through hole 7. For this reason, it is possible to reduce the displacement of the solder balls during the process without increasing the number of solder ball mounting processes at all, and to improve the production yield.

In the first embodiment of the present invention, the case where the solder ball 6 has a diameter of about 700 microns has been described. However, the present invention is not limited to this. Even if the size changes, the through hole 7
And the outer diameter of the mounting metal pad 4 can be adjusted.

Next, B according to the second embodiment of the present invention will be described.
A GA type semiconductor device will be described with reference to FIG.

FIG. 3 is a sectional view of a BGA type semiconductor device.

In FIG. 3, the same portions as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 3, the structure of the upper surface of the multilayer ceramic substrate is the same as that of FIG.

On the other hand, on the back surface of the multilayer ceramic substrate 1,
A solder ball mounting metal pad 4 having a thickness of about 15 μm is formed in a hollow flat plate and functions as a holding means for the solder ball 6. The solder ball mounting metal pad 4 is electrically connected to the substrate upper surface electrode 13 on the upper surface of the multilayer ceramic substrate 1 via the internal wiring 15 in the multilayer ceramic substrate 1.

Further, a part is fitted into a flat hollow portion in the solder ball mounting metal pad 4, and a solder ball 6 is placed thereon. The solder balls 6 are connected and fixed to the hollow flat-plate-shaped solder ball mounting metal pads 4 by the molten and solidified solder 5A. Here, the solder ball 6 has a diameter of 70
0 μm, the outer diameter of the solder ball mounting metal pad 4 is about 800 μm in diameter, and the inner diameter of the flat hollow portion is about 200 μm.

According to the above-described semiconductor device according to the second embodiment of the present invention, the solder ball 6 has a bottom portion on the back surface of the multilayer ceramic substrate 1 and a side portion on the side edge of the solder ball mounting metal pad 4 hollow portion. , And the upper portion is fixed with the solder 5A melted and solidified thereon, so that it is very stable against external force.

Further, since the position of the solder ball is stable as described above, the amount of the melted and solidified solder 5A is smaller than that in the case where the solder 5A is mounted on a conventional flat metal pad. Sufficient stability can be ensured. Also,
Since the amount of solder paste is sufficiently small, there is no short circuit between adjacent solder balls or metal pads for mounting solder balls.

Next, the method of manufacturing the semiconductor device will be described with reference to FIG.
This will be described in detail with reference to FIG.

FIGS. 4 (1A) to 4 (4A) are top views showing the steps of mounting the solder ball 6 on the solder ball mounting metal pad 4 formed in the hollow disk shape of the mounting portion of the multilayer ceramic substrate 1. It is shown.

FIGS. 4 (1B) to 4 (4B) show X in FIG. 4 (1A) to 4 (4A) indicated by a dashed line.
FIG. 4 shows cross-sectional views at a Y portion.

Hereinafter, the same portions as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

First, the inner diameter 20 is formed on the multilayer ceramic substrate 1.
A disk-shaped solder ball mounting metal pad 4 having a hollow portion of about 0 μm and an outer shape of about 800 μm is formed by sintering. Here, the solder ball mounting metal pad 4 is desirably formed to be thick to place the solder ball 6 thereon, and has a thickness of about 15 μm (FIG. 4 (1A), FIG.
B)).

Subsequently, a hollow disk-shaped solder paste film 5 having a thickness of about 150 μm is formed on the solder ball mounting metal pad 4 by screen printing (FIG. 4).
(2A), FIG. 4 (2B)).

Next, a solder ball 6 having a diameter of about 700 μm is placed in the hollow portion of the solder ball mounting metal pad 4 (FIGS. 4A and 4B).

Further, the solder ball 6 is heated and melted, and then solidified by cooling. The solder ball 6 is fixed in the hollow disk-shaped metal pad 4 for mounting the solder ball by the melted and solidified solder 5A (FIG. 4 (4A)). 4 (4B)).

According to the above manufacturing method, the solder balls 6
Is mounted in the hollow portion of the solder ball mounting metal pad 4, so that it can be mounted stably without shifting laterally. For this reason, the position shift of the solder ball during the process can be reduced without increasing the number of solder ball mounting processes at all, and the manufacturing yield can be improved. Further, the formation of the hollow metal pad can be easily performed by partial thick-film copper plating, and there is no inconvenience in manufacturing. Further, the semiconductor device used in the related art can be implemented by simply changing the outer plating and applying a thick film plating to the portion of the metal pad 4 for solder ball mounting, so that the process can be easily changed.

FIGS. 5 and 6 show a modification of the second embodiment of the present invention. 5 (1) and 6 (1) show top views of the metal pad 4, and FIGS. 5 (2) and 6 (2)
Shows a top view when solder balls are mounted on each of them. FIG. 5A shows an arrangement in which four rectangular flat metal pads 4 are arranged instead of the upper surface of the metal pad 4 having the hollow disk shape shown in FIG. 4A, and FIG. , Three rectangular flat metal pads 4 are arranged. Even in this case, as shown in FIGS. 5 (2) and 6 (2), a portion surrounded by four or three metal pads 4 functions as a solder ball holding means, and the solder ball 6 is stably mounted. Can be placed.

The shape of the metal pad 4 may be a hollow rectangular shape as shown in FIG. When such metal pads 4 are arranged on the back surface of the semiconductor device, FIG.
As shown in FIG. 9B and FIG. 9B (embodiment shown in FIG. 7), the arrangement of the metal pads 4 is compared with each other. When 4 are arranged, the same number of metal pads can be arranged in the same area. In addition, since the area per one of the metal pads 4 can be increased, the application area of the solder paste 5 can be widened. Accordingly, a relatively large amount of solder can be used without causing a short circuit between the metal pads 4 with the same solder paste film thickness, and the stability of the solder ball can be improved.

Further, as shown in FIG. 8, a pad having a circular hollow portion and a rectangular outer shape may be used. When such metal pads 4 are arranged on the back surface of the semiconductor device, FIG.
(Embodiment shown in FIG. 4) and FIG. 9 (C) (Embodiment shown in FIG. 8) by comparing the arrangement diagrams of the metal pads, as shown in FIG. When the metal pads 4 are arranged, the same number of metal pads can be arranged in the same area and the same effect as in the example shown in FIG. Further, since the area of the metal pad can be further increased than the shape shown in FIG. 7, the application area of the solder paste 5 can be made wider.

In the above-described second embodiment of the present invention, the case where the solder ball 6 has a diameter of about 700 microns has been described. However, the present invention is not limited to this. Even when the size is changed, it can be implemented by adjusting the inner diameter, outer diameter, and thickness of the solder ball mounting metal pad 4.

[0064]

As described above, according to the present invention, a semiconductor device which is resistant to external impacts and a semiconductor device which does not cause displacement of solder balls and short-circuit between adjacent solder balls does not occur. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a process top view and a process cross-sectional view of a manufacturing process of the semiconductor device according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a process top view and a process cross-sectional view of a manufacturing process of a semiconductor device according to a second embodiment of the present invention.

FIG. 5 is a part of a top view showing a solder ball mounting metal pad and a solder ball mounting state according to a modification of the second embodiment of the present invention.

FIG. 6 is a part of a top view showing a solder ball mounting metal pad and a solder ball mounting state according to a modification of the second embodiment of the present invention.

FIG. 7 is a top view of a modified example of the solder ball mounting metal pad according to the second embodiment of the present invention.

FIG. 8 is a top view of a modification of the solder ball mounting metal pad according to the second embodiment of the present invention.

FIG. 9 is an in-plane arrangement diagram of a semiconductor device rear surface of a solder ball mounting metal pad according to a second embodiment of the present invention.

FIG. 10 is a cross-sectional view and a top view of a conventional BGA.

FIG. 11 is a process top view and a process cross-sectional view of a conventional BGA manufacturing method.

[Explanation of symbols]

 1 multilayer ceramic substrate (mounting substrate) 1A multilayer ceramic substrate base 1B multilayer ceramic substrate outermost layer 3 electrode film 4 solder ball mounting Metal pad 5 Solder paste film 5A Solder melted and solidified 6 Solder ball 7 Through hole (recess) 11 Semiconductor pellet 12 · Bonding wire 13 ··· Board top electrode 14 ··· Cap 15 ··· Internal wiring 21 ··· Semiconductor pellet electrode

Claims (5)

[Claims] A mounting substrate having a first surface and a second surface opposite to the first surface; a semiconductor pellet mounted on the first surface of the mounting substrate; A substrate upper surface electrode formed on one surface and electrically connected to the semiconductor pellet electrode on the semiconductor pellet; and a substrate upper surface electrode formed on the second surface of the mounting substrate and electrically connected to the substrate upper surface electrode. A lower surface electrode of the substrate; and a solder ball electrically connected to the lower surface electrode of the substrate. The solder ball is in contact with the side surface of the solder ball on the second surface of the mounting substrate around the solder ball and holds the solder ball. A semiconductor device having a solder ball holding means. 2. The solder ball holding means according to claim 1, wherein the solder ball holding means includes a protrusion around the solder ball on the second surface of the mounting substrate, the protrusion being in contact with the side surface of the solder ball. Semiconductor device. 3. The semiconductor device according to claim 1, wherein a portion of the second surface of the mounting board, which is in contact with the side surface of the solder ball, forms a recess as the solder ball holding means. 4. A metal film having a hollow portion for holding a solder ball is formed around the solder ball on a second surface of the mounting board as the solder ball holding means. The semiconductor device according to claim 1. 5. A step of mounting a semiconductor pellet on a first surface of a mounting substrate, wherein the second surface of the mounting substrate opposite to the first surface is in contact with a side surface of a solder ball and holds the solder ball. Forming a solder paste film around the solder ball holding means, solder balls in which a part is fitted to the solder ball holding means and is in contact with the solder paste film And a step of melting and solidifying the solder paste film and fixing the side surface portion of the solder ball to the solder ball holding means.