JPH09275162A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a fail of a bump electrode due to a thermal stress by a difference in the heat swelling coefficient of an IC chip and a chip support substrate and a mounting substrate in a semiconductor device in which the IC chip is provided on one face side of the chip support substrate and a number of bump electrodes are provided on the other face side thereof. SOLUTION: In a bump electrode 5A near an outer peripheral edge 23 of an IC chip out of a number of bump electrodes 5 of a chip support substrate 3, for example, an In-Sn low melting point alloy having the melting point at 177 deg.C is used, and in the other bump electrode 5B, in order to secure a mechanical strength between a semiconductor device and a mounting substrate, for example, a Pb-Sn alloy having a melting point at 255 deg.C is used. Incidentally, the bump electrode 5A has the same effect even if using gold instead of the low melting alloy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure in which, for example, spherical or columnar protruding electrodes are arranged on the surface opposite to the surface on which a semiconductor integrated circuit chip is provided on a chip supporting substrate,
Alternatively, the present invention relates to a semiconductor device having a structure in which the protruding electrodes are arranged on a semiconductor integrated circuit chip and a method for manufacturing the semiconductor device.

[0002]

2. Description of the Related Art As a typical semiconductor package, an IC (semiconductor integrated circuit) chip (die) cut out from a semiconductor wafer is bonded onto a chip support substrate called a die pad and the chip support is also provided. There is known a structure in which a large number of external leads arranged around the substrate and an IC chip are connected by wires and the whole is molded. By the way, recently, BGA (Ball
Semiconductor devices called “Grid Array” type package chips or LGA (Land Grid Array) type package chips are being put to practical use.

This type of semiconductor device is constructed by mounting an IC chip on one surface of a chip supporting substrate and arranging a large number of protruding electrodes in a grid pattern on the other surface of the chip supporting substrate instead of external leads. Is. FIG. 10 is a view of this semiconductor device viewed from the other surface side of the chip support substrate 11, and the outer peripheral edge of the IC chip is shown as a solid line 12 for convenience. Protruding electrode 1
3 is made of, for example, a Pb-Sn alloy, and has projection electrodes 13 and I
The C chip is electrically connected by a bonding wire on one surface side of the chip support substrate 11 and a wiring in the chip support substrate 11.

According to such a semiconductor device, since the protruding electrodes 13 are arranged in a plane, the number of electrodes can be increased,
Therefore, there is an advantage that the entire package can be downsized while increasing the degree of integration of the IC chip, and the electrode and the IC
There is also an advantage that the distance to the chip can be shortened and the speed of signal transfer can be increased.

[0005]

However, when a semiconductor device such as a BGA or LGA type is mounted on a substrate and subjected to a temperature cycle test, the protruding electrodes near the outer peripheral edge of the IC chip tend to be defective. The cause is IC
Since the material of the chip is silicon and the material of the chip supporting board and the mounting board is glass epoxy, they have different thermal expansion coefficients, so that each interface between the IC chip, the chip supporting board, the protruding electrode and the mounting board is different. It is considered that this is due to the stress applied according to the thermal strain.

The largest stress is generated in the area corresponding to the outer peripheral edge of the IC chip, and therefore the electrode pad made of, for example, copper foil, which is the end of the wiring on the other surface of the chip support substrate, is crimped to the protruding electrode. The contact resistance may increase even if the connection part or the connection part between the protruding electrode and the mounting substrate is peeled off or is not peeled off. Such a phenomenon is caused by IC
It is most likely to occur in the vicinity of the outer peripheral edge of the chip, and is relaxed toward the inner side of the IC chip arrangement region.

A semiconductor device may be placed in a harsh environment. For example, when the semiconductor device is incorporated in an automobile,
It can reach temperatures as high as 25 ° C. Therefore, when the above-described semiconductor device is used, there is a possibility that an electrode defect may occur and the reliability is low.

The present invention has been made under such circumstances, and an object thereof is to obtain high reliability in a semiconductor device having a large number of protruding electrodes.

[0009]

According to the present invention, there is provided a semiconductor device including a semiconductor integrated circuit chip and a large number of protruding electrodes electrically connected to the semiconductor integrated circuit chip, for example, a protruding electrode on a chip support substrate. The present invention is directed to a semiconductor device having a structure in which the semiconductor integrated circuit chip is arranged on a surface opposite to the surface on which the semiconductor integrated circuit chip is provided, or a structure in which the protruding electrodes are arranged on the semiconductor integrated circuit chip. It is characterized in that the protruding electrodes of the part are made of a material different from that of the other protruding electrodes.

Here, different materials for the protruding electrodes mean that
For example, when the protruding electrodes in the area corresponding to the high temperature area of the semiconductor integrated circuit chip are made of a material having higher thermal conductivity than other protruding electrodes, or when some protruding electrodes have a higher resistance value than other protruding electrodes. The case where it is made of a material having a low

In the semiconductor device according to the present invention, the protruding electrodes are arranged on the surface of the chip supporting substrate opposite to the surface on which the semiconductor integrated circuit chip is provided. The semiconductor integrated circuit chip also includes a protruding electrode located near the outer peripheral edge made of a highly viscous material. In this case, the protruding electrode absorbs the stress due to thermal strain to prevent the defective protruding electrode. There is an effect that can be done. As an example of a highly viscous material,
A low melting point metal can be mentioned.

Further, the present invention is also directed to a method of manufacturing such a semiconductor device, which method uses a first vacuum suction device having a first suction hole, and uses the first vacuum suction device.
A step of vacuum-adsorbing the granular body to be the first protruding electrode to the suction hole of the second suction electrode and press-bonding it to the electrode pad; and using the second vacuum suction device in which the second suction hole is formed, A step of vacuum-adsorbing the granular body to be the second protruding electrode in the adsorption hole and press-bonding it to the remaining electrode pad.

[0013]

1 and 2 show a semiconductor device according to a first embodiment of the present invention. However, the number of protruding electrodes does not correspond to the limitation of the figure. Reference numeral 2 in the drawing denotes an IC chip (die), which is bonded to one surface side of the chip support substrate 3 with a paste agent. Chip support substrate 3
Is made of glass epoxy, and electrode pads 31 and 32 made of, for example, copper foil are formed on one surface side and the other surface side, and a wiring formed in the chip support substrate 3 between these electrode pads 31 and 32 ( (Not shown) electrically connected. The electrode pad 21 of the IC chip 2 and the electrode pad 31 on the one surface side of the chip support substrate 3 are connected by the bonding wire 22, and the region including the IC chip 2 and the bonding wire 22 is molded by the molding resin 4. .

The electrode pads 32 on the other surface side of the chip support substrate 3 are arranged, for example, in a grid pattern, and a large number of spherical protruding electrodes 5 are pressure-bonded to these electrode pads 32. Of these protruding electrodes 5, for the first protruding electrode 5A shown by the diagonal lines near the outer peripheral edge portion 23 of the IC chip 2 (indicated by a solid line in FIG. 2 for convenience), for example, In is 48
%, Sn, 52%, and a low melting point In—Sn alloy having a melting point of 117 ° C. is used. For the second protruding electrodes 5B other than the protruding electrodes 5A, which are shown in white, Pb
Containing 60% of Sn and 40% of Sn and having a melting point of 225 ° C.
A b-Sn alloy is used.

The spherical diameter of each of the protruding electrodes 5 is, for example, about 0.2 to 0.65 mm, and the vertical and horizontal arrangement intervals are about 0.5 to 1.5 mm. Protruding electrode 5
The method of crimping A and 5B to the other surface of the chip support substrate 3 is as follows.
For example, the steps shown in FIGS. 3 and 4 are performed. 6 in the figure
Reference numeral A denotes a first vacuum suction device, which includes a suction plate 62 in which first suction holes 61 are arranged. The first suction holes 61 are arranged corresponding to the arrangement of the electrode pads 32 on the other surface side of the chip support substrate 3 near the outer peripheral edge of the IC chip 2.

Reference numeral 6B in the drawing is a second vacuum suction device, which is equipped with a suction plate 64 in which the second suction holes 63 are arranged. The second suction holes 63 are arranged corresponding to the arrangement of the electrode pads 32 on the other surface side of the chip support substrate 3 other than the electrode pads 32 near the outer peripheral edge of the IC chip 2.

First, using the first vacuum suction device 6A, as shown in FIG.
As shown in FIG. 4, the In—Sn alloy particles, eg, spherical bodies 60A, which become the first protruding electrodes 6A, are vacuum-sucked in the first suction holes 61, and the vacuum suction device 6A is pressed toward the chip support substrate 3 side. The spherical body 60A is pressure-bonded to the electrode pad 32 near the outer peripheral edge of the IC chip 2. Thereafter, the vacuum suction is released, the vacuum suction device 6A is separated from the chip support substrate 3, and thus the first protruding electrode 6A is formed on the chip support substrate 3.

Next, using the second vacuum suction device 6B, the Pb- which becomes the second protruding electrode 6B in the second suction hole 63 is formed.
A granular body of Sn alloy, for example, a spherical body 60B is vacuum-sucked, and the vacuum suction device 6B is pressed against the chip support substrate 3 side to press-bond the spherical body 60B to the remaining electrode pad 32. Then, the vacuum suction is released, and the vacuum suction device 6B is attached to the chip support substrate 3
And the second protruding electrode 6B is thus formed on the chip support substrate 3. When pressing the spherical bodies 60A and 60B,
The chip support substrate 3 is heated to about 200 ° C.

When the semiconductor device described above is mounted on a substrate and the semiconductor device is placed in a high temperature environment where the temperature of the projecting electrodes 5 exceeds, for example, 100 ° C., thermal expansion between the IC chip 2 and the chip support substrate 3 and the mounting substrate is performed. IC chip 2 due to the difference in coefficient
Although a large stress is generated between the mounting substrate and the IC chip 2 near the outer peripheral edge of the IC chip 2, the protruding electrode 5A near the outer peripheral edge of the IC chip 2 is made of a low melting point alloy having a melting point of 117 ° C. Therefore, the viscosity is high, so that part of the stress is absorbed by the protruding electrode 5A and
A deforms. As a result, the protruding electrode 5 and the chip support substrate 3
Since the stress applied to the interface between the mounting substrate and the chip supporting substrate 3 is small, the stress applied to the interface between the mounting substrate and the chip supporting substrate 3 is small, and the stress applied to the interface between the mounting electrode and the mounting substrate is small. Absent.

An alloy having a high melting point is used for the second protruding electrodes 5B other than the first protruding electrodes 5A, and since the viscosity is low, the characteristics required for mounting the semiconductor device on the substrate, for example, under high temperature. The second projecting electrode 5B is responsible for ensuring the mechanical strength of the semiconductor device. Therefore, the electrode failure does not occur and the mechanical strength is ensured, so that the semiconductor device has an effect of high reliability.

Such a configuration in which the materials are made different between the electrodes cannot be adopted in a semiconductor device of a type in which one plate is punched out to form a chip support substrate (die pad) and external leads, but the protruding electrode is used. Any semiconductor device of the type in which the chips are arranged on the chip support substrate can be adopted. In the above-described embodiment, focusing on this point,
Only the protruding electrode 5A near the outer peripheral edge of the C chip 2 is formed of a low melting point alloy. In this case, in the present invention, not only the low melting point alloy but also the material having a large viscosity such as gold may be used to form the first protruding electrode 5A. In this case, compared to the case where all the protruding electrodes 5 are made of gold, the cost is low. Is advantageous. Further, when forming the first protruding electrode 5A with a low melting point alloy, a material that increases the viscosity of the protruding electrode 5A when the semiconductor device is used may be selected, and there is no problem in the mechanical strength of the protruding electrode 5. Not only the first protruding electrodes 5A but all the protruding electrodes may be made of a low melting point alloy. The shape of the protruding electrode is not limited to a spherical shape, and may be a cylindrical shape or the like.

Here, in order to confirm the effect of the present invention, the following test was conducted. The material of the first protruding electrode 5A contains 38% of Pb and 62% of Sn, and has a melting point 183.
A semiconductor device using a Pb-Sn alloy at a temperature of C is used as Example 1 and the first protruding electrode 5A is made of In of 48% and S
A semiconductor device using an In—Sn alloy with a melting point of 117 ° C. containing 52% of n is set as Example 2. As the material of the other protruding electrode (second protruding electrode 5B), Pb is 60%,
A Pb—Sn alloy containing 40% Sn and having a melting point of 225 ° C. was used. In addition, a semiconductor device in which all the protruding electrodes were formed of this Pb-Sn alloy was used as a comparative example.

Each of these three types of semiconductor devices has five types.
Prepare 0 each and mount it on a printed circuit board.
After being placed in a low temperature environment of 5 ° C. for 10 minutes, placed in a high temperature environment of 150 ° C. for 10 minutes, and a temperature cycle test of −65 ° C. → 150 ° C. was performed once, and the temperature cycle test was repeated until electrode failure of the protruding electrode occurred. . FIG. 5 shows the number of temperature tests in which the electrode failure of the bump electrode occurred, together with the material of the bump electrode.

As can be seen from FIG. 5, in the comparative example, the melting point of the protruding electrode 5A near the outer peripheral edge of the IC chip is 225 ° C.
Since the protrusion electrode 5A has a small viscosity at a high temperature because a high Pb-Sn alloy is used, a large thermal stress acts on the interface described above, and the temperature cycle test is performed at 2900.
An electrode defect has occurred at a point of time up to 3500 times. Regarding the other protruding electrodes 5B, the thermal stress is not so large as in the vicinity of the outer peripheral edge of the IC chip.
Although it withstands up to 700 times, the durability of the entire semiconductor device is determined by 2900 to 3500 times of the protruding electrode 5A.

On the other hand, in Examples 1 and 2, since low melting point alloys having melting points of 183 ° C. and 117 ° C. are used as the protruding electrodes 5A, respectively, the protruding electrodes 5A have large viscosity at high temperature, and therefore thermal stress is high. It is absorbed by the protruding electrode 5A. As a result, the number of temperature cycle tests leading to electrode failure is 3700 to 4400 times in Example 1, which is considerably larger than that in Comparative Example, and in Example 2, no electrode failure occurs even after 6000 times. It can be seen that the semiconductor device of the present invention has high durability and high reliability.

Next, second and third embodiments of the present invention will be described with reference to FIGS. 6 and 7, respectively. FIG.
In the semiconductor device shown in FIG. 5, the protruding electrode 5C (indicated by diagonal lines) is located in a region of the protruding electrode 5 on the other surface side of the chip support substrate 3 that corresponds to the region of the IC chip where the temperature becomes high, that is, the region where the temperature becomes high. The protruding electrode) is made of a metal having a high thermal conductivity, such as Au, Ag, or Cu, which forms a heat-dissipating electrode, and other materials of the protruding electrode 5 have a low thermal conductivity because there is little demand for heat dissipation, For example, the Pb (60%)-Sn (40%) alloy described above is used. Thus, the reliability of the semiconductor device is improved by using the heat-dissipating electrode, and the metal having high thermal conductivity is expensive. Therefore, the cost increase can be suppressed by using the heat-dissipating electrode only in the high temperature region. You can

Further, in the semiconductor device shown in FIG. 7, of the protruding electrodes 5 on the other surface side of the chip support substrate 3, the protruding electrodes 5D (projected electrodes shown by hatched lines) of the transmission line which are required to increase the signal transmission speed. Is made of a metal having a low resistance value, for example, gold, and as the material of the other protruding electrodes 5, for example, the Pb (60%)-Sn (40%) alloy is used. With this configuration, high-speed processing can be achieved because the signal transmission can be speeded up, and since materials such as gold are expensive, the cost increase can be suppressed by using gold only at necessary parts. be able to. Although resistance can be reduced by using gold as the protruding electrode 5, the low resistance protruding electrode is not limited to a portion where high speed signal transmission is required, and does not drop at a portion where a signal level is low. It is effective to use to

As described above, according to the present invention, of the many protruding electrodes, a material which is required is used for a portion where a demand for heat dissipation or speeding up of a signal is great.
As the target semiconductor device, as in the fourth embodiment shown in FIG. 8, a protruding electrode 72 made of a conductive material such as a metal is directly pressure-bonded to the electrode pad 71 of the IC chip 7 cut out from the semiconductor wafer. FC (Flip Chi
p) or the like, or the insulating layer 8 on the surface of the IC chip 8 as in the fifth embodiment shown in FIG.
1 is formed, and the protruding electrodes 82 are arranged and provided on the surface of the insulating layer 81, and the protruding electrodes 82 and the electrode pads of the IC chip 8 which are not visible in the drawing are electrically connected by the wiring in the insulating layer 81. , DCA (Direct Chip
Also included are types called Attach). In the example of FIG. 8, the protruding electrode 72A (painted in black) is made of gold for high-speed transmission,
In the example of FIG. 9, the protruding electrode 82A (painted in black)
Is made of gold to serve as a heat dissipation electrode.

[0029]

As described above, according to the present invention, among the protruding electrodes on the other surface of the chip support substrate, the protruding electrodes in the region corresponding to the outer peripheral edge of the IC chip are made of a highly viscous material. Since the stress corresponding to the thermal strain is absorbed by the protruding electrode, it is possible to suppress the contact failure and peeling of the protruding electrode,
High reliability can be obtained. Moreover, since the material of the protruding electrode is made different from the material of the other protruding electrodes as needed, it is possible to keep the cost low while ensuring heat dissipation and low resistance.

[Brief description of drawings]

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

FIG. 2 is a bottom view showing the semiconductor device according to the first embodiment of the present invention.

FIG. 3 is a vertical cross-sectional side view showing the manufacturing process of the semiconductor device according to the first embodiment of the invention.

FIG. 4 is a vertical cross-sectional side view showing the manufacturing process of the semiconductor device according to the first embodiment of the invention.

FIG. 5 is a table showing the results of temperature tests conducted to confirm the effects of the present invention.

FIG. 6 is a bottom view showing a semiconductor device according to a second embodiment of the present invention.

FIG. 7 is a bottom view showing a semiconductor device according to a third embodiment of the present invention.

FIG. 8 is a perspective view showing a semiconductor device according to a fourth embodiment of the present invention.

FIG. 9 is a perspective view showing a semiconductor device according to a fifth embodiment of the present invention.

FIG. 10 is a bottom view showing a conventional semiconductor device.

[Explanation of symbols]

 2 integrated circuit chip 21 electrode pad 22 bonding wire 23 outer peripheral edge of integrated circuit chip 3 chip support substrate 31, 32 electrode pad 4 mold resin 5 protruding electrode 5A first protruding electrode 5B second protruding electrode 6A first vacuum adsorption Device 6B Second vacuum suction device 61 First suction hole 63 Second suction hole 5C, 5D Projection electrode 7,8 Integrated circuit chip 81 Insulating layer 72, 72A, 82, 82A Projection electrode

Claims (6)

[Claims] 1. A semiconductor device comprising a semiconductor integrated circuit chip and a large number of protruding electrodes electrically connected to the semiconductor integrated circuit chip, wherein some of the plurality of protruding electrodes are replaced by other protruding electrodes. The semiconductor device is made of a material different from that of the bump electrode. 2. The semiconductor device according to claim 1, wherein some of the plurality of protruding electrodes are made of a material having higher thermal conductivity than the other protruding electrodes. 3. The semiconductor device according to claim 1, wherein some of the plurality of protruding electrodes are made of a material having a resistance value lower than that of the other protruding electrodes. 4. A semiconductor integrated circuit chip provided on one surface side of a chip support substrate, and a large number of protruding electrodes provided on the other surface side of the chip support substrate and electrically connected to the semiconductor integrated circuit chip. A semiconductor device comprising: a plurality of protruding electrodes, wherein the protruding electrodes located near the outer peripheral edge of the semiconductor integrated circuit chip are made of a highly viscous material. 5. The semiconductor device according to claim 4, wherein the highly viscous material is a low melting point metal. 6. A semiconductor device comprising: a semiconductor integrated circuit chip; and a plurality of projecting electrodes electrically connected to the semiconductor integrated circuit chip and crimped to electrode pads formed on an electrode supporting surface, respectively. Using a first vacuum suction device in which a first suction hole is formed, a step of vacuum-sucking a granular body to be a first protruding electrode in the first suction hole and crimping the granular body to the electrode pad; Using a second vacuum suction device in which two suction holes are formed, a step of vacuum-sucking a granular body to be the second protruding electrode in the second suction hole and pressure-bonding to the remaining electrode pad; A method of manufacturing a semiconductor device, comprising: