JP2501278B2 - Semiconductor package - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor package using an aluminum nitride multilayer substrate.

[0002]

2. Description of the Related Art Semiconductor chips are usually packaged by a ceramic multilayer substrate or the like for the purpose of protection from the external environment and improvement of handling. By the way, there is an increasing demand for miniaturization of various electronic devices, and as semiconductor chips become highly integrated,
There is also a strong demand for miniaturization and high density of the semiconductor package itself. Further, in order to cope with the high speed operation of the semiconductor chip, it is necessary to shorten the wiring length ratio in the package and reduce the signal delay. From this point also, the miniaturization of the semiconductor package is required.

Further, the number of input / output signals per element tends to increase with the high integration and high speed of semiconductor chips. Further, some semiconductor chips are also being increased in power consumption, and the amount of heat generated from the semiconductor chips is increasing with the increase in integration and power consumption of these semiconductor chips. It is strongly desired to improve heat dissipation.

In response to various demands for such a semiconductor package, in order to cope with the increase in the number of input / output signals, that is, the increase in the number of pins after downsizing the package itself, a cavity for accommodating a semiconductor chip is provided. A so-called cavity-up type semiconductor package in which a lead pin is joined to the surface opposite to the surface on which the cavity is formed is advantageous, while opening to the upper side. A ceramic multilayer wiring board is usually used as the body of the semiconductor package.

However, in the case of the cavity-up type semiconductor package described above, it is difficult to directly bond the radiation fin to the upper surface like the cavity-down type semiconductor package, and even if the radiation fin is bonded. Since heat cannot be directly transferred, it is disadvantageous in terms of heat dissipation. That is, in the cavity-up type semiconductor package, even if the heat radiation fins or the heat radiation members are attached to the side where the cavities are formed, the heat must be released from the semiconductor chip to the heat radiation fins or the heat radiation member once via the package body. And, in a general semiconductor package, heat dissipation decreases as the size is reduced, and in a cavity-up type semiconductor package, it is difficult to secure a sufficient heat dissipation path area especially when the size is reduced. This leads to a further decrease in heat dissipation.

In view of this, it is conceivable that the heat dissipation path is expanded by increasing the thickness of each layer of the ceramic multi-layer substrate which is the package body. In this case, however, the following problems occur. Occurs. That is, in order to speed up the circuit operation, it is indispensable to consider the wiring layer in the package as a transmission line and control its characteristic impedance. Here, the characteristic impedance of the transmission line is determined by the inductance of the transmission line and the capacitance between the transmission line and the ground. That is, the characteristic impedance of the wiring layer in the semiconductor package using the ceramic multilayer substrate is determined by the volume (thickness × width) of the wiring layer and the thickness of each layer. Therefore, if the layer thickness is changed in order to increase the heat dissipation path area, not only the package design (circuit design) is fundamentally changed, but also the outer shape itself may have to be changed depending on the wiring density. Therefore, there is a possibility that miniaturization of the package cannot be achieved.

[0007]

As described above, the conventional cavity-up type semiconductor package can cope with an increase in the number of input / output signals of the semiconductor chip and a reduction in the size of the package itself. As a result, it is difficult to ensure sufficient heat dissipation, and as a result, the high integration and speeding up of semiconductor chips have not been fully addressed. It is also possible to increase the thickness of each layer of the ceramic multilayer substrate in order to improve heat dissipation, but in this case it is necessary to change the circuit design, and it is against the miniaturization of the package. However, this is not a practical solution because it causes various problems.

The present invention has been made in order to solve such a problem, and achieves the increase in the number of input / output signals and the miniaturization of the package, and the heat radiation without causing an electrical design change. It is an object of the present invention to provide a semiconductor package which is capable of practically corresponding to high integration and high speed of a semiconductor chip, which has a significantly improved property.

[0009]

A semiconductor package of the present invention includes a semiconductor element mounted on one surface thereof, and an aluminum nitride multilayer substrate having a wiring pattern electrically connected to the semiconductor element, and the semiconductor element. A sealing member joined to one surface of the aluminum nitride multilayer substrate so as to be sealed, and electrically connected to the wiring pattern, and on the other surface or one surface of the aluminum nitride multilayer substrate. In a semiconductor package having a connection terminal provided, the aluminum nitride multilayer substrate, an aluminum nitride wiring layer provided with internal wiring,
The aluminum nitride heat transfer layer not including the internal wiring layer is laminated and integrated in the thickness direction. Further, the aluminum nitride multilayer substrate is characterized by having an aluminum nitride wiring layer provided with internal wiring and an aluminum nitride heat transfer layer not including an internal wiring layer thicker than the aluminum nitride wiring layer.

[0010]

In the semiconductor package of the present invention, the package main body is composed of an aluminum nitride wiring layer provided with an internal wiring layer and an aluminum nitride heat transfer layer for forming a heat radiation path which does not include the internal wiring layer. An aluminum multilayer substrate is used. By using such an aluminum nitride multilayer substrate, the electrical characteristics such as the characteristic impedance of the internal wiring can be designed without considering the heat dissipation, and the miniaturization can be achieved. Also,
The heat dissipation of the package itself, that is, the area of the heat dissipation path can be sufficiently ensured. Therefore, it is possible to reduce the size of the package while supporting high integration and high speed of the semiconductor element.

[0011]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a semiconductor package of an embodiment in which the present invention is applied to a PGA (pin grid array) structure. Semiconductor package 1 shown in FIG.
On the upper surface 2a of the aluminum nitride multilayer substrate 2
A semiconductor chip 3 such as a power IC or the like is mounted, and a lead pin 4 is bonded to a lower surface 2b of the aluminum nitride multilayer substrate 2 as a connection terminal. The upper surface 2a of the aluminum nitride multilayer substrate 2 on which the semiconductor chip 3 is mounted is covered with a sealing member having a U-shaped cross section that also serves as a heat dissipation member, for example, an aluminum nitride sealing member 5.

The above-mentioned aluminum nitride multilayer substrate 2 is a multilayer wiring substrate constituted by integrating a plurality of aluminum nitride layers into multilayers. Each layer is provided with an internal wiring layer 6 having a predetermined wiring pattern. Aluminum nitride wiring layer 7 and aluminum nitride heat transfer layer 8 which is simply an aluminum nitride layer without providing internal wiring
Can be divided into In other words, the aluminum nitride multilayer substrate 2 is composed of a plurality of aluminum nitride wiring layers 7 provided with the internal wiring layer 6 and a plurality of aluminum nitride heat transfer layers 8 which basically function as heat radiation paths. ing. The aluminum nitride wiring layer 7 also functions as a part of the heat dissipation path.

Here, the state of heat transfer from the semiconductor chip 3 is schematically shown in FIG. As shown in FIG. 2, heat generated by the operation of the semiconductor chip 3 (arrow A in the figure)
Is once passed through the aluminum nitride multilayer substrate 1 (in the figure,
After being transmitted to the sealing member 5 made of aluminum nitride that also serves as a heat radiation member, it is diffused in the air (arrow C in the figure). Therefore, since the thickness t of the aluminum nitride multilayer substrate 2 directly affects the heat dissipation path area, the thickness t of the aluminum nitride multilayer substrate 2 is controlled by the aluminum nitride heat transfer layer 8.
By increasing the thickness, it is possible to significantly improve the heat dissipation of the semiconductor package 1.

From the viewpoint of internal wiring, since the aluminum nitride multilayer substrate 2 can be composed of only the aluminum nitride wiring layer 7, the thickness of the aluminum nitride wiring layer 7 is set only based on the circuit design. can do. Therefore, the conventional circuit design can be used without being changed and the external size can be reduced without being affected by the dimensional change due to the improvement of the heat dissipation property, that is, the influence of the increase of the thickness of the aluminum nitride heat transfer layer 8. be able to.

Such an aluminum nitride multilayer substrate 2
Is produced by, for example, simultaneously firing a conductive material that will be each aluminum nitride wiring layer 7 and internal wiring layer 6 and each aluminum nitride heat transfer layer 8.

The internal wiring layer 6 includes a via hole 6a filled with a conductive substance, and the surface wiring layer 9 formed on the semiconductor chip mounting surface 2a of the aluminum nitride multilayer substrate 2 and the via hole 6a. It is electrically connected via. Since the surface wiring layer 9 enables high-density wiring, it is preferable to use thin film wiring using a thin film forming technique such as a sputtering method or a vapor deposition method. The mounted semiconductor chip 3 is electrically connected to the surface wiring layer 9 via a bonding wire 10. The lead pin 4 is bonded to the lower surface 2b of the aluminum nitride multilayer substrate 2 so as to be electrically connected to the internal wiring layer 6.

The semiconductor chip mounting surface 2a of the aluminum nitride multilayer substrate 2 is covered with the aluminum nitride sealing member 5 as described above, and the mounted semiconductor chip 3 has the aluminum nitride sealing member 5 formed thereon. It is hermetically sealed by. That is, in the aluminum nitride sealing member 5, the end surface of the convex outer edge portion 5a having a U-shaped cross section is brought into contact with the semiconductor chip mounting surface 2a of the aluminum nitride multilayer substrate 2, and the semiconductor chip 3 is placed in the concave portion 5b. It is joined so as to be housed, and the concave portion 5b serves as a cavity of the conventional semiconductor package. The aluminum nitride multilayer substrate 2 and the aluminum nitride sealing member 5 are joined by Au-Sn solder, Pb-Sn solder, sealing glass, or the like. When soldering, the surfaces to be joined are metallized in advance. Further, in the case of bonding with sealing glass, the thickness is preferably 100 μm or less so that the bonding layer does not hinder heat transfer.

The aluminum nitride sealing member 5 also has a function as a heat radiating member and contributes to a reduction in the number of parts. Also, the aluminum nitride sealing member 5
Since the joint area (area of the end surface of the convex outer edge portion 5a) directly affects the heat transfer state from the aluminum nitride multilayer substrate 2 to the aluminum nitride sealing member 5, the formation accuracy of the surface wiring layer 9 and It is preferable to set the size as large as possible in consideration of the allowable size of the semiconductor package 1 (including the formation pitch of the lead pins 4). Also, the sealing member 5
The aluminum nitride sintered body, which is the constituent material of the sealing material 5, has essentially high thermal conductivity. However, since various materials having different thermal conductivities can be obtained depending on the raw material and manufacturing conditions, The aluminum nitride sintered body of
It is preferable to use one having a higher thermal conductivity.

As a constituent material of the sealing member 14, a mullite sintered body, a silicon carbide sintered body, or the like can be used. Further, instead of these ceramic materials, it is also possible to use a metal sealing member having high thermal conductivity, such as a W-Cu-based sealing member obtained by impregnating porous tungsten with copper. However, when the aluminum nitride multilayer substrate 2 and the sealing member 5 are made of aluminum nitride of the same material, the occurrence of cracks and the reduction of the bonding force due to the difference in thermal expansion between them does not occur. A highly reliable semiconductor package can be realized.

On the aluminum nitride sealing member 5 described above, a radiation fin as conventionally used can be attached. As a constituent material of this heat radiation fin, a metal material such as an aluminum material, an aluminum nitride sintered body of the same material as the sealing member, or the like can be used.
When the heat radiation fin is made of an aluminum nitride sintered body, it can be integrally formed with the sealing member 5.

In the semiconductor package 1 of the above-described embodiment, the semiconductor chip 3 is bonded and mounted on the surface 2a of the aluminum nitride multilayer substrate 2 opposite to the lead pin bonding surface 2b. It is possible to increase the number and increase the number of pins. Since only the aluminum nitride wiring layer 7 needs to be taken into consideration in the circuit design, the conventional circuit design can be used. Even when the wiring density is high, the package can be downsized and the aluminum nitride heat transfer layer 8 can sufficiently secure the heat dissipation path, so that excellent heat dissipation can be obtained. You can

Regarding the heat dissipation of the semiconductor package 1, the sealing member 5 is made of an aluminum nitride sintered body, the sealing member 5 has a U-shaped cross section, and the aluminum nitride multilayer substrate 2 is Since the joint area (heat transfer area) of is increased, the heat from the semiconductor chip 3 can be more efficiently dissipated. As described above, it can be said that the semiconductor package 1 of the above-described embodiment can be miniaturized and have a large number of pins, and at the same time, can satisfy the high heat dissipation.

3 and 4 show a modification of the semiconductor package 1 of the above embodiment. That is,
The aluminum nitride multi-layer substrate 2 is, as shown in FIG.
A plurality of aluminum nitride heat transfer layers 8 are provided so that the required heat dissipation path area, in other words, the thickness t of the multilayer substrate 2 can be obtained.
May be laminated, or as shown in FIG.
With only one layer of aluminum nitride heat transfer layer 8, it is possible to obtain the required thickness t of the multilayer substrate 2 in terms of heat dissipation.
Further, as shown in FIG. 4, the aluminum nitride wiring layer 2
Of these, only the lowermost aluminum nitride layer 11 may be thick. In this case, the lowermost aluminum nitride layer 11 is an aluminum nitride heat transfer layer that also serves as a wiring layer.

The semiconductor packages of the above-mentioned respective embodiments are
In both cases, the semiconductor chip 3 is mounted on the aluminum nitride multilayer substrate 2
However, the present invention is also effective for a normal cavity-up type semiconductor package 20 as shown in FIG. 5, for example.

In the semiconductor package 20 shown in FIG. 5, an aluminum nitride multilayer substrate 21 having a cavity 21a is provided.
The semiconductor chip 3 is housed in the cavity 21a. The cavity 21a is hermetically sealed by a plate-shaped aluminum nitride sealing member 22 that also serves as a heat dissipation member. Then, the aluminum nitride multilayer substrate 21
Except for the cavity forming layer 23, the plurality of aluminum nitride wiring layers 24 and the plurality of aluminum nitride heat transfer layers 25
It is composed of Also in such a cavity-up type semiconductor package 20, the same effect as that of the semiconductor package 1 described above can be obtained.

Next, a specific example of the semiconductor package of the above embodiment will be described. Example 1 First, an aluminum nitride green sheet having a thickness of 0.5 mm was prepared, and a sulu hole was formed in each sheet according to the circuit design. Next, among these green sheets, for the aluminum nitride wiring layer 7, the conductor paste is applied in a desired wiring shape, the sulu holes are filled with the conductor paste, and the aluminum nitride heat transfer layer 8 is formed. For the products, only the conductive paste was filled into the sulu holes.

Next, after laminating these aluminum nitride green sheets, they are fired in a reducing atmosphere (simultaneous firing of aluminum nitride and conductor layers) to form a 25 mm × 25 mm × 2.6 mmt aluminum nitride multilayer having an internal wiring layer 6. Substrate 2 was obtained. In this aluminum nitride multilayer substrate 2, the total thickness of the aluminum nitride wiring layer 7 is 1.5 mm.
The total thickness of the aluminum nitride heat transfer layer 8 was 1.1 mm.

Next, after the surface wiring layer 9 is formed on the upper surface 2a of the aluminum nitride multilayer substrate 2 by the thin film method, the lead pins 4 are formed on the lower surface 2b side of the aluminum nitride multilayer substrate 2.
Were joined at a joining pitch of 1.27 mm using Ag low. Thereafter, a TEG chip for measuring thermal resistance as a semiconductor chip 3 is bonded and mounted on the upper surface 2a of the aluminum nitride multilayer substrate 2,
A bonding wire 10 was attached to complete the electrical connection.

On the other hand, the sealing member 5 (outer diameter: 25 mm ×, which also functions as a heat dissipation member) is made of an aluminum nitride sintered body of 170 W / m K.
25 mm × 3 mm t) was produced. Then, the aluminum nitride sealing member 5 is joined to the upper surface 2a of the aluminum nitride multilayer substrate 2 on which the semiconductor chip 3 is mounted by a soldering method, and a desired semiconductor package (structure shown in FIG. 1) is obtained. Obtained.

Further, as a comparison with the present invention, the aluminum nitride heat transfer layer 8 is not used and the aluminum nitride wiring layer 7 is used.
A semiconductor package (thickness of the multi-layer substrate: 1.5 mm) was produced in the same manner as in the example except that the aluminum nitride multi-layer substrate was composed of only this.

The heat dissipation of the semiconductor packages according to the examples and comparative examples thus obtained was measured by the ΔV _BE method after mounting the semiconductor chip, and the thermal resistance in the semiconductor package according to the comparative example was set to 1. At that time, the semiconductor package according to the example had a thermal resistance of 0.62.
Thus, it is clear that the semiconductor package of the present invention has excellent heat dissipation.

Next, another embodiment of the present invention will be described with reference to FIG.
Will be described with reference to.

In the semiconductor package 30 shown in FIG. 6, lands 31 are provided as connection terminals on the lower surface 2b of the aluminum nitride multilayer substrate 2 and have a so-called LGA (land grid array) structure. This land 31
Is composed of solder bumps and the like. In addition,
The structure is the same as that of the semiconductor package 1 shown in FIG. 1 except that the land 31 is used as the connection terminal. The aluminum nitride multilayer substrate 2 has an aluminum nitride wiring layer 7 having an internal wiring layer 6 and an internal wiring layer. The aluminum nitride heat transfer layer 8 does not include

The present invention is also effective for a semiconductor package having such an LGA structure, and as in the semiconductor package of the above-described embodiment, excellent heat dissipation can be obtained. In each of the above-described embodiments, the example in which the present invention is applied to the semiconductor package having the structure in which the connection terminal is provided on the surface opposite to the mounting surface of the semiconductor chip has been described. The present invention can be applied to a semiconductor package provided on the same surface as the surface.

[0036]

As described above, according to the present invention, a semiconductor having a large number of pins and a small package, and having significantly improved heat dissipation without causing an electrical design change or the like. Package can be provided. Therefore, it is possible to provide a semiconductor package that can practically correspond to high integration and high speed of semiconductor chips.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a semiconductor package of an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a heat transfer state in the semiconductor package shown in FIG.

FIG. 3 is a cross-sectional view showing a configuration of a modified example of the semiconductor package shown in FIG.

FIG. 4 is a cross-sectional view showing the configuration of another modification of the semiconductor package shown in FIG.

FIG. 5 is a sectional view showing a configuration of a semiconductor package according to another embodiment of the present invention.

FIG. 6 is a cross-sectional view showing the structure of a semiconductor package of still another embodiment of the present invention.

[Explanation of symbols]

 1, 20, 30 ... Semiconductor package 2 ... Aluminum nitride multi-layer substrate 3 ... Semiconductor chip 4 ... Lead pin 5 ... Aluminum nitride sealing member that also functions as a heat dissipation member 6 ... Internal wiring layer 7, 24 ... Nitriding Aluminum wiring layer 8, 25 ... Aluminum nitride heat transfer layer 9 ... Surface wiring layer 10 ... Bonding wire 11 ... Aluminum nitride heat transfer layer 31 also serving as wiring layer 31 ... Land

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kotoshi Sato 8 Shinshinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Toshiba Corporation Yokohama office (56) Reference JP-A-5-114665 (JP, A) JP-A 5-243417 (JP, A)

Claims (2)

(57) [Claims] 1. An aluminum nitride multilayer substrate having a semiconductor element mounted on one surface thereof and having a wiring pattern electrically connected to the semiconductor element, and the aluminum nitride multilayer substrate so as to seal the semiconductor element. A semiconductor package comprising a sealing member bonded to one surface of the aluminum nitride, and a connection terminal electrically connected to the wiring pattern and provided on the other surface of the aluminum nitride multilayer substrate or on the one surface. In the aluminum nitride multilayer substrate, an aluminum nitride wiring layer provided with internal wiring and an aluminum nitride heat transfer layer not containing the internal wiring layer are laminated and integrated in the thickness direction. Characteristic semiconductor package. 2. An aluminum nitride multilayer substrate having a semiconductor element mounted on one surface thereof and having a wiring pattern electrically connected to the semiconductor element, and the aluminum nitride multilayer substrate so as to seal the semiconductor element. A semiconductor package comprising a sealing member bonded to one surface of the aluminum nitride, and a connection terminal electrically connected to the wiring pattern and provided on the other surface of the aluminum nitride multilayer substrate or on the one surface. 2. The semiconductor package according to claim 1, wherein the aluminum nitride multilayer substrate has an aluminum nitride wiring layer provided with internal wiring, and an aluminum nitride heat transfer layer that does not include an internal wiring layer thicker than the aluminum nitride wiring layer.