JPH10275879A - Semiconductor package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the mounting reliability of a semiconductor chip and bonding reliability of a radiating fin and improve the electrical characteristics of a signal wiring, increase in wiring density and so on, in addition, reduce the manufacturing cost particularly in a semiconductor package, wherein a semiconductor chip of high power consumption and so on are mounted. SOLUTION: A ceramic substrate 4, where a semiconductor chip is mounted, is bonded to one major surface (lower surface) 2a of a metallic support substrate 2. A resin wiring base material 10, including a wiring layer 9a is bonded and fixed at the side where the ceramic substrate 4, is bonded of the metallic support substrate 2. A semiconductor chip 5 is bonded to the ceramic substrate 4 and is supported by the metallic support substrate 2 via the ceramic substrate 4. The semiconductor chip 5 is electrically connected to the wiring layer 9a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor package which realizes a reduction in signal wiring resistance, a high wiring density, a low package cost, and the like, and also has an improved bonding reliability of a semiconductor element and a radiation fin. About.

[0002]

2. Description of the Related Art With the progress of semiconductor manufacturing technology in recent years,
2. Description of the Related Art Semiconductor elements tend to be highly integrated, operate at higher speeds, consume more power, and have more terminals, and the performance and functions of semiconductor elements are also rapidly improving. As described above, a package on which a highly functional semiconductor element, particularly a semiconductor element with high power consumption is mounted, is required to have high heat dissipation in order to operate without deteriorating the element function.

[0003] At present, inexpensive plastic packages are predominant as packages, but in the case of plastic packages, the power consumption that can be applied by itself is low, and in order to cope with the increase in power consumption, heat sinks and radiation fins are used. There is a need. In addition, since the plastic package has a large difference in thermal expansion coefficient from that of the semiconductor element, there is a possibility that cracking or the like may occur when a large semiconductor element is mounted.

[0004] For these reasons, ceramic packages are mainly used when mounting a semiconductor device with high power consumption and large size. For example, in a package using alumina ceramics, W-Cu
Generally, a heat sink made of an alloy is used. In a package using aluminum nitride ceramics or the like having high thermal conductivity, a package in which a semiconductor element is directly mounted on an aluminum nitride substrate is used.

In various semiconductor packages as described above, in order to efficiently remove the heat generated in the semiconductor element, a package having a cavity-down (face-down) structure in which the semiconductor element is joined to the lower surface side of the package base is used. It is valid. According to the package having such a structure, heat can be directly removed from the back side of the semiconductor element,
Further, the use of the radiation fins allows the heat taken from the semiconductor element to be efficiently radiated.

[0006] In recent years, the sophistication of semiconductor elements has made power consumption higher than expected. For example, if the power consumption of a semiconductor device is 5W or less, it is possible to reduce the thermal resistance without using a radiation fin or cooling fan.
At that point, those measures become unavoidable. Regarding this point, the package of the face-down structure described above is easy to install the radiation fins, so regardless of the plus chip package and the ceramic package
A semiconductor package having a face-down structure can be said to be a package structure suitable for a semiconductor element of high power consumption type.

However, the positive chip package has a large difference in thermal expansion coefficient from that of the semiconductor element as described above, and is liable to crack, particularly when a large semiconductor element is mounted. It has the disadvantage of being inferior. On the other hand, although the conventional ceramic package is excellent in terms of mounting reliability, the signal wiring is mainly routed by the co-fired conductor layer with the ceramic substrate,
Wiring resistance tends to be high, and there is a limit in increasing the wiring density. In addition, there is a problem that the manufacturing cost is high.

In order to cope with such circumstances, for example, a semiconductor package using both a ceramic substrate having high thermal conductivity and a resin wiring board such as a printed board has been proposed (IMC 1996, Proceedings p24-27). In this semiconductor package, a heat spreader made of aluminum nitride is used, a semiconductor element is mounted on the lower surface side, a resin wiring board is joined therearound, and signal wiring of the semiconductor element is routed in a wiring layer of the resin wiring board. It was made.
Such a semiconductor package is expected as a package capable of achieving high power consumption of a semiconductor element, low resistance and high density of signal wiring, low cost of a package, and the like.

However, in a semiconductor package using the above-described aluminum nitride substrate as a heat spreader, when a semiconductor device having a device size of, for example, 20 mm square is mounted, the aluminum nitride substrate must be enlarged accordingly. When metal radiating fins are joined to the entire upper surface of such a large aluminum nitride substrate, cracks may occur due to the difference in thermal expansion between the aluminum nitride substrate and the metal radiating fins when a thermal cycle is applied. is there.

On the other hand, a semiconductor package using a metal plate such as a copper plate for a heat spreader has also been proposed. However, since a copper plate has a large difference in thermal expansion coefficient from that of a semiconductor device, when a heat cycle is applied, the semiconductor device cannot be used. There is a high risk of damaging the device.

[0011]

As described above, a semiconductor package using a high thermal conductive ceramic such as an aluminum nitride substrate or a metal plate such as a copper plate as a heat spreader and using a resin wiring substrate as a wiring layer includes a semiconductor package. It is expected to be a package that can achieve high power consumption of elements, low resistance and high density of signal wiring, low cost of packages, and the like. However, if only heat conductive ceramics are used for the heat spreader, the bonding reliability of the radiating fins decreases in the face-down structure, which is originally expected as a high heat radiating package. There is a problem that the mounting reliability of the element is reduced.

SUMMARY OF THE INVENTION The present invention has been made to address such a problem, and has achieved an improvement in electrical characteristics of signal wiring, an increase in wiring density, and a reduction in manufacturing cost. It is an object of the present invention to provide a semiconductor package which can improve both the mounting reliability of a semiconductor element and the bonding reliability of a heat radiation fin, and in particular, has improved adaptability to a semiconductor element with high power consumption.

[0013]

According to the present invention, there is provided a semiconductor package comprising: a metal supporting substrate having a ceramic substrate serving as a semiconductor element mounting portion joined to one main surface; and a ceramic supporting substrate of the metal supporting substrate. A resin wiring base joined and fixed to the joining surface side and having a wiring layer; and a semiconductor element supported by the metal supporting substrate via the ceramic substrate and electrically connected to the wiring layer. It is characterized by:

In the semiconductor package of the present invention, a ceramic substrate serving as a semiconductor element mounting portion is joined to a metal supporting substrate, and the semiconductor element is mounted on the metal supporting substrate via the ceramic substrate. Although the metal support substrate generally has a large difference in thermal expansion coefficient from the semiconductor element, the ceramic substrate plays a role as a thermal expansion relaxation layer because the thermal expansion coefficient of the ceramic substrate is close to that of the semiconductor element. Therefore, the mounting reliability of the semiconductor element can be improved.

The heat generated in the semiconductor element can be transmitted to the metal supporting substrate via the ceramic substrate, so that high heat dissipation can be achieved. In addition, even when the metal radiating fins are attached, the metal radiating fins are joined to the metal supporting substrate, so that the thermal history reliability and the like of the joints can be greatly improved.
Further, since the signal wiring is routed by the wiring layer provided on the resin wiring base material, by using copper or the like for this wiring layer, it is possible to reduce the resistance of the signal wiring, increase the wiring density, and the like. In addition, since the resin substrate has a lower dielectric constant than the ceramic substrate, the electrical characteristics of the wiring in the package can be improved. Further, by arranging the signal wiring with the resin wiring base material, the manufacturing cost of the semiconductor package can be reduced.

[0016]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional view showing a schematic structure of an embodiment of the semiconductor package of the present invention. The semiconductor package 1 shown in FIG. 1 has a metal support substrate 2. For the metal supporting substrate 2, a metal material having excellent thermal conductivity such as copper, copper alloy, aluminum, and aluminum alloy is used. Such a metal supporting substrate 2 is provided with a cavity 3 on one main surface, that is, on the lower surface 2a side, and a ceramic substrate 4 serving as a semiconductor element mounting portion is joined in the cavity 3. The cavity 3 is provided as needed, and a single-plate-shaped metal support substrate may be used as long as a region for forming an external connection terminal described later can be secured.

Then, on the lower surface of the ceramic substrate 4,
The semiconductor element 5 is joined with its back side up.
That is, the semiconductor element 5 is mounted and supported via the ceramic substrate 4 on the metal supporting substrate 2 so as to form a face-down structure. Here, the semiconductor element 5 to be mounted is not limited, but the power consumption is, for example, 3W.
The present invention is particularly effective for a large-sized semiconductor device with high power consumption, such as a high device size of 10 mm square or more. In the semiconductor package of the present invention, such a semiconductor element 5 can be mounted with high reliability.

The ceramic substrate 4 serving as a semiconductor element mounting portion includes an aluminum nitride (AlN) sintered body, a silicon nitride (Si ₃ N ₄ ) sintered body, an alumina (Al ₂ O ₃ ) sintered body, Various ceramic materials such as a SiC) sintered body, a boron nitride (BN) sintered body, and diamond can be used. Here, although the metal supporting substrate 2 generally has a large difference in thermal expansion coefficient from the semiconductor element 5, the thermal expansion coefficient of the ceramic substrate 4 is close to that of the semiconductor element 5.
The ceramic substrate 4 also functions as a thermal expansion relaxation layer. Therefore, the mounting reliability of the semiconductor element 5 can be improved.

As described above, the ceramic substrate 4 plays a role as a thermal expansion relaxation layer between the metal supporting substrate 2 and the semiconductor element 5, and also has a function as a heat transfer layer. Therefore, the ceramic substrate 4 has an AlN sintered body, a Si ₃ N ₄ sintered body, a SiC sintered body which has a thermal expansion coefficient similar to that of the semiconductor element (Si) 5 and is excellent in thermal conductivity.
A sintered body or the like is preferably used.

Of these, the AlN sintered body is a preferable material for achieving high heat dissipation of the semiconductor package 1 because of its high thermal conductivity. As the AlN sintered body used for the ceramic substrate 4, one having a thermal conductivity of 70 W / mK or more, which is generally used as a substrate material, is preferably used. In addition, since the Si ₃ N ₄ sintered body has both high strength characteristics and relatively good thermal conductivity, it is a preferable material for achieving high reliability and high heat dissipation of the semiconductor package 1. Si ₃ N ₄ used for the ceramic substrate ₄
As the sintered body, one having a thermal conductivity of 50 W / m K or more is particularly preferable. A Si ₃ N ₄ sintered body is well known as a high-strength and high-toughness ceramic sintered body. Further, for example, silicon nitride powder used as a raw material of the sintered body is finely divided, highly purified, a sintering aid composition, and the like. By controlling the composition of Si ₃ N ₄ sintered body with relatively high thermal conductivity of 50 W / m K or more without impairing the mechanical properties such as high strength and high toughness. can get.

The ceramic substrate 4 preferably has an outer peripheral shape substantially similar to that of the semiconductor element 5. That is, in order to suppress a defect caused by a difference in thermal expansion between the ceramic substrate 4 and the metal supporting substrate 2, specifically, cracking of the ceramic substrate 4 when a thermal cycle is applied, the ceramic substrate 4 and the metal Since it is advantageous that the bonding area with the supporting substrate 2 is smaller, it is advantageous to dispose the ceramic substrate 4 only in a region necessary for bonding the semiconductor element 5, in other words, to mount the semiconductor element 5 by bonding. It is preferable to reduce the area of the ceramic substrate 4 as much as possible.

The ceramic substrate 4 is basically a substrate having no single-layered wiring layer. However, when the metal support substrate 2 is used as a ground or when the ceramic substrate 4 is provided with a ground layer. Alternatively, a metallized layer or a through hole may be formed on the ceramic substrate 4.

The ceramic substrate 4 and the metal supporting substrate 2 can be joined by, for example, a brazing method using an active metal, a method in which the ceramic substrate 4 is metallized and then joined using solder or a general brazing material; The bonding can be performed via the bonding layer 6 made of these, such as a bonding method using a general resin-based adhesive. When the metal supporting substrate 2 is made of copper or a copper alloy, the so-called DBC method (Direct
It is also possible to directly bond the ceramic substrate 4 to the metal supporting substrate 2 by applying a bonding cupper method). The ceramic substrate 4 and the semiconductor element 5 are made of a brazing material,
They are joined via a joining material layer 7 such as solder or glass-based adhesive.

On the lower surface 2 a of the metal support substrate 2, which is the semiconductor element mounting surface, except for the cavity 3,
A resin wiring base material 10 in which a conductor layer 9 is formed on a resin film 8 with a copper foil or the like is bonded and fixed via an adhesive layer 11.
Here, as the resin film 8, a film having a thickness of about 20 to 100 μm made of various insulating resins such as a liquid crystal polymer, a polyimide resin, and a glass epoxy resin can be used. Among them, a liquid crystal polymer is particularly preferably used in the invention because it has a low dielectric constant and is inexpensive. Further, for the adhesive layer 11, a thermosetting resin sheet, a thermosetting resin paste, or the like can be used.

In the semiconductor package 1 of this embodiment, conductor layers 9a and 9b are formed on both surfaces of the resin film 8 by thermocompression bonding of a metal foil such as a copper foil having a thickness of about 12 μm. Of these, the lower conductor layer 9a, that is, the conductor layer made of copper foil or the like on the outermost surface is etched into a desired wiring pattern and functions as a wiring layer.
The upper conductor layer 9b, that is, the conductor layer on the side of the metal support substrate 2 is for improving the bonding property with the metal support substrate 2 and for forming a microstrip line. I do. Further, the surface of the lower conductor layer 9a may be insulatively coated with an insulating resin or the like except for an electrical connection portion.

The lower conductor layer 9 a of the resin wiring substrate 10, that is, the wiring layer, is electrically connected to the electrodes of the semiconductor element 5 via the bonding wires 12. The wiring layer 9
A conductive ball 13 such as a Pb-Sn-based solder ball or an In-based solder ball is joined to the other end side of "a". These conductive balls 13 function as external connection terminals. Note that, as the conductive ball 13, various types of conductive balls having at least a surface having conductivity, such as a metal ball and a metal-coated resin ball, can be used.

That is, the electrodes of the semiconductor element 5 are electrically connected to the conductive balls 13 as external connection terminals via the wiring layer 9a of the resin wiring base 10 and the bonding wires 12. The signal wiring is basically routed by the wiring layer 9a of the resin wiring base material 10. The semiconductor element 5 including the bonding wire 12 is sealed with a potting resin 14 or the like.

As described above, the semiconductor package 1 of this embodiment constitutes a BGA package having a face-down structure. Semiconductor package 1 of this embodiment
Is mounted on a mounting board such as a multilayer printed circuit board. At this time, the conductive balls 13 as the external connection terminals of the semiconductor package 1 are electrically connected to the wiring layers of the mounting board to form a semiconductor mounted component.

In the semiconductor package 1 described above, 3 W
In the case of the semiconductor element 5 of a degree, although the resin film 8 becomes a heat resistance layer, the conductive balls 13 and the resin wiring base 10 are used.
Since the heat can be transmitted to the mounting board through the wiring layer 9a, specifically, a copper foil or the like, it can be used without using a radiation fin. Further, when the high power consumption semiconductor element 5 is mounted, as shown in FIG. 2, the heat radiation fins 15 are bonded to the other main surface, that is, the upper surface 2 b side of the metal support substrate 2 via the adhesive layer 16. By doing so, sufficient heat dissipation can be ensured.

At this time, the radiating fins 15 are usually made of copper, copper alloy, aluminum, aluminum alloy or the like. In the semiconductor package 1 of this embodiment, the bonding surface of the metal radiating fins 15 is a metal supporting substrate. 2 provided. Therefore, for example, even when the semiconductor element 5 having an element size of 40 mm square is mounted and the metal supporting substrate 2 has to be enlarged accordingly, the joining portion of the metal radiating fins 15 is a metal-metal joint. Therefore, the joining reliability of the metal radiating fins 14 can be greatly improved.

In the semiconductor package 1 of the above-described embodiment, the metal support substrate 2 is used as the substrate for supporting the resin wiring substrate 10, and the semiconductor element 5 is interposed via the ceramic substrate 4 having a thermal expansion coefficient similar to that of the metal support substrate. First, the semiconductor element 5 is mounted on the metal support substrate 2 by bonding.
The mounting reliability can be greatly improved by the intermediate ceramic substrate 4 as compared with the case where the substrate is directly joined to the metal supporting substrate.

Regarding the heat dissipation of the semiconductor package 1,
Basically, it has a face-down structure capable of efficiently removing heat generated in the semiconductor element 5,
Since heat transfer from the semiconductor element 5 to the metal supporting substrate 2 is not hindered by the ceramic substrate 4, good heat dissipation can be obtained. Also, when the metal radiating fins 15 are joined, as described above,
Since metal bonding is performed, bonding reliability of the metal radiating fins 15 when a thermal cycle is applied can be sufficiently ensured. In addition, with respect to the joining portion between the ceramic substrate 4 and the metal supporting substrate 2, sufficient reliability can be obtained by minimizing the size of the ceramic substrate 2 as far as the semiconductor element 5 can be mounted.

The wiring layer 9a provided on the resin film 8
As described above, a metal foil such as a copper foil having a thickness of 100 μm or less can be used. According to a metal foil such as a copper foil, the wiring resistance and high-frequency characteristics of the signal wiring can be significantly improved as compared with a fired layer of W or Mo, which is generally used as an internal wiring layer of a ceramic substrate. Can be. Further, by etching and patterning a copper foil or the like, high-density wiring such as a wiring width of 30 μm and a distance between wirings of 20 μm can be realized. Also, the signal wiring can be easily arranged.

Further, since the signal wiring is basically routed by the wiring layer 9a of the resin wiring base 10, the metal supporting substrate 2 and the ceramic substrate 4 should be basically a single-plate supporting substrate. Therefore, the manufacturing cost and manufacturing man-hour of the ceramic substrate 4 can be greatly reduced as compared with the conventional ceramic multilayer wiring substrate in which complicated multilayer wiring is formed inside, and the manufacturing cost of the semiconductor package 1 can be reduced. Can be reduced.

As described above, the semiconductor package 1 having the BGA structure according to this embodiment achieves low resistance and high density of signal wiring, low cost of the package, high heat dissipation, and the like, and then the semiconductor element 5 The mounting reliability of
Further, when the metal radiating fins 15 are joined, the joining reliability can be improved.

The semiconductor package 1 having such a face-down structure was manufactured as a package having a power consumption of 5 W and mounting a 400-pin semiconductor element. First, a resin wiring substrate 10 was prepared in which a liquid crystal polymer was used as a main component and copper foils were thermocompressed on both surfaces thereof. The copper foil serving as the wiring layer 9a was etched to form a pattern, and an insulating resin was coated thereon. The other copper foil was left as it was. The thickness of the resin wiring substrate 10 is 0.14 mm, and chip mounting is compatible with wire bonding.

The ceramic substrate 4 has a thermal conductivity of 180
W / m K AlN ceramics were used. Substrate thickness is 0.6
mm and the size is 10 mm square. Such an AlN ceramic substrate 4 was bonded to an Al support substrate 2 having an outer shape of 41 mm square and a thickness of 0.3 mm using an epoxy adhesive. The above-described resin wiring substrate 10 was further joined to such an Al support substrate 2 using an epoxy-based adhesive. Then, using a silver paste on the AlN ceramic substrate 4
The semiconductor element 5 of 5 W, 400 pins was joined and wire-bonding was carried out to obtain the semiconductor package 1 of this embodiment.

On the other hand, as a comparative example of the present invention, a semiconductor package (Comparative Example 1) having the same structure as that of the above-described embodiment except that a single plate of AlN ceramics is used for the support substrate,
A semiconductor package (Comparative Example 2) having a structure similar to that of the above-described example except that an aluminum single plate was used as the support substrate was manufactured.

An aluminum radiating fin (39 mm square, 18 mm high) 15 was bonded to the semiconductor package of the above-described embodiment and the semiconductor packages of Comparative Examples 1 and 2 with an adhesive, respectively, and subjected to a temperature cycle test. The temperature cycle test is
One cycle of 228K-room temperature-393K was applied for 1000 cycles. Ten tests were performed for each example, and those in which cracks occurred between the support substrate and the Al radiating fins and those in which cracks occurred between the support substrate and the semiconductor element were measured. Table 1 shows the results together with the thermal resistance ratio of the package. Note that the thermal resistance ratios in Table 1 are relative values when the embodiment is set to 1.

[0041]

[Table 1] As is clear from Table 1, the semiconductor package according to the example of the present invention has not only excellent thermal resistance but also excellent bonding (mounting) reliability of the semiconductor element and the radiation fin as compared with Comparative Example 1. . Also, it can be seen that the heat radiation fins are excellent in bonding property also to Comparative Example 2.

Next, another embodiment of the present invention will be described with reference to FIGS. 3, 4 and 5. FIG.

As shown in FIG. 3, the resin wiring substrate is not limited to the above-mentioned resin film having copper foil or the like adhered thereto, but may be a resin wiring substrate having a wiring layer 17a such as an internal wiring layer or a surface wiring layer. A so-called printed wiring board 17 can be used. The other configuration is the same as that of the above-described embodiment. However, in terms of increasing the wiring density, for example, a thickness of 100 μm
It is preferable to use a metal foil as described below, which is attached by thermocompression bonding or the like.

As shown in FIG. 4, a single-plate-shaped metal substrate is used for the metal support substrate 2.
A space for accommodating the ceramic substrate 4 and the semiconductor element 5 may be formed by interposing a spacer 18 made of a ceramic plate, a metal plate, or the like between the substrate and the printed wiring board 17. This structure can be applied to the above-described embodiment.

Further, as shown in FIG.
The electrical connection between the wire and the wiring layer can be made using a so-called TAB lead 19 or the like instead of the bonding wire 12. Since the TAB leads 19 are supported by the TAB tape 20, the TAB tape 20 can be used as a resin base material. In this case, the semiconductor element 5
A so-called TAB chip is used.

As described above, the semiconductor package of the present invention is applicable to various forms. Further, the present invention is not limited to the BGA package of the semiconductor package of the present invention, and can be applied to a package or the like in which external connection terminals other than conductive balls are used.

[0047]

As described above, according to the semiconductor package of the present invention, the resistance of the signal wiring is reduced, the density thereof is increased, the manufacturing cost is reduced, and the heat dissipation is further improved. The mounting reliability of the element can be improved, and when the heat radiation fins are bonded, the bonding reliability can be improved. According to such a semiconductor package,
For example, a large-sized semiconductor element with high power consumption can be packaged with high reliability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic structure of an embodiment of a semiconductor package of the present invention.

FIG. 2 is a sectional view showing a modification of the semiconductor package shown in FIG.

FIG. 3 is a cross-sectional view illustrating a schematic structure of another embodiment of the semiconductor package of the present invention.

FIG. 4 is a sectional view showing a modification of the semiconductor package shown in FIG. 3;

FIG. 5 is a sectional view showing a schematic structure of still another embodiment of the semiconductor package of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Semiconductor package 2 ... Metal support substrate 4 ... Ceramic substrate 5 ... Semiconductor element 8 ... Resin film 9 ... Conductor layer 9a ... Wiring layer 10 ... Resin wiring base material 13 Conductor ball 15 Heat dissipation fin

Claims (4)

[Claims] A metal support substrate having a ceramic substrate serving as a semiconductor element mounting portion bonded to one main surface thereof; a wiring layer fixedly bonded to the metal support substrate at a bonding surface side of the ceramic substrate; And a semiconductor element supported by the metal supporting substrate via the ceramic substrate and electrically connected to the wiring layer. 2. The semiconductor package according to claim 1, wherein a metal radiating fin is bonded to a side of said metal supporting substrate opposite to said ceramic substrate bonding surface. 3. The semiconductor package according to claim 1, wherein an external connection terminal is provided on a wiring layer of the resin wiring base. 4. The semiconductor package according to claim 1, wherein the metal supporting substrate is made of one selected from copper, a copper alloy, aluminum and an aluminum alloy, and the ceramic substrate is made of aluminum nitride, silicon nitride, A semiconductor package comprising, as a main component, at least one selected from silicon carbide, boron nitride, and diamond.