JP3526614B2 - Semiconductor device - 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 device having excellent heat dissipation.

[0002]

2. Description of the Related Art As a semiconductor device is highly integrated and has a large capacity, a heat generation amount of a semiconductor chip is increasing. As shown in FIG. 8 , a semiconductor chip 1 is mounted on a heat spreader 2 in a resin-sealed type. Semiconductor devices are used. The heat spreader 2 is made of a metal material such as Cu or 42% Ni—Fe alloy (42Ni alloy) having good thermal conductivity in order to exert the heat radiation effect of the semiconductor chip 1.
In the semiconductor device of FIG. 8 , the semiconductor chip 1 is bonded to the heat spreader 2 with a bonding material 19 such as Ag paste, and is also connected to the inner leads 16 and bonding wires 17. The heat spreader 2 is connected to the inner leads 16 with a bonding material 20 made of an insulating material, and these are sealed with a resin 18. Also,
In some cases, the bottom surface of the heat spreader 2 is exposed from the resin 18. The other end of the inner lead 16 extends from the resin 18 to form the outer lead 24, and the solder 25 is attached thereto. When mounting such a resin-encapsulated semiconductor device on the circuit board 26, it is subjected to so-called reflow processing, which melts the solder 25 by heat irradiation or heating. The heat spreader 2 may also be called a heat sink, a header, or the like.

When the semiconductor device is subjected to reflow processing, the boundary between the heat spreader 2 and the resin 18 may be separated due to the difference in thermal expansion between them, or the resin at the boundary may be cracked. The water content may expand and cracks in the resin may expand. In general, a sealing resin for semiconductor devices, which has hygroscopicity such as epoxy resin, is used, and therefore tends to absorb moisture over time. Then, water easily accumulates at the boundary between the resin 18 and the heat spreader 2. When this is subjected to a reflow treatment, the moisture abruptly expands due to heating, and as shown in FIG. 8 , cracks 27 mainly occur at the corners of the heat spreader 2.

Conventionally, various means for solving such a problem have been proposed. First, as a solution to the problem due to the difference in thermal expansion between the resin and the heat spreader, Japanese Patent Laid-Open No. 4-293
No. 60 discloses a semiconductor device having a thermal expansion coefficient close to that of the Si semiconductor device.
2Ni alloy is used for the lead frame, it has good thermal conductivity, and its thermal expansion coefficient is close to that of 42Ni alloy, Mo, W, A.
It has been proposed to use 1N in a heat spreader. Further, as a measure for preventing resin peeling and cracking, Japanese Patent Laid-Open No. 1-5043 discloses that a heat spreader includes an organic film such as a polyimide resin or an epoxy resin, or alumina or silica in the film. It is described that a film containing a metal oxide is formed, and Japanese Patent Application Laid-Open No. 4-25052 discloses an insulating inorganic polymer compound such as a polyimide-based insulating organic polymer compound and a low melting point glass. Forming a film is described in each.

[0005]

The technique of Japanese Patent Laid-Open No. 4-29360, which proposes a solution to the problem due to the difference in thermal expansion between the resin and the heat spreader in the above-mentioned prior art, is used for the heat spreader. Mo,
Since the thermal conductivity of W and AlN is lower than that of Al and Cu,
A problem remains as a high-speed and large-capacity semiconductor device. Regarding the film of the heat spreader, JP-A-1-50
The organic film as disclosed in Japanese Patent Laid-Open No. 43-43 has hygroscopicity, and the glass film as disclosed in Japanese Patent Laid-Open No. 4-25052 has a problem in film strength. It is an object of the present invention to provide a high-speed and large-capacity semiconductor device which has excellent heat dissipation and solves the problems of resin peeling and cracking during reflow processing.

[0006]

A semiconductor device of the present invention for achieving the above object is a resin in which a semiconductor chip, a heat spreader on which the semiconductor chip is mounted, and an inner lead connected to the semiconductor chip are sealed with a resin. In the encapsulated semiconductor device, the heat spreader is composed of a composite of Fe-based metal and Cu-based metal, the Cu-based metal is vertically penetrated and embedded, and the heat spreader has a Si spray coating. In addition, the radiation fins are exposed and mounted on the heat spreader on the opposite side of the semiconductor chip. In addition, it is preferable that the heat spreader is enclosed in a resin, and the Cu-based metal that constitutes the heat spreader is a plurality of strip-shaped bodies that spread to the left and right.

On the other hand, the heat spreader is made of a composite of Fe-based metal and Cu-based metal, and the Cu-based metal is vertically penetrated and buried.
A structure in which a Cu-based metal is embedded in a mixed state with the Cu-based metal and the Cu-based metal vertically penetrates may be used.

[0008]

The present invention will be described below with reference to the drawings. As shown in the example of FIG. 1, the semiconductor device of the present invention includes a semiconductor chip 1, a heat spreader 2 on which the semiconductor chip 1 is mounted,
In the resin-sealed semiconductor device in which the inner lead 16 connected to the semiconductor chip 1 with the bonding wire 17 is sealed with the resin 18, the heat spreader 2 is made of Fe.
It is composed of a composite of the system metal 3 and the Cu system metal 4, and the Cu system metal 4 penetrates vertically and is embedded. The example in FIG. 1 is Cu
A plurality of pillars of the base metal 4 (three visible in the cross section of the figure) are vertically embedded at the mounting position of the semiconductor chip 1 and embedded. The semiconductor chip 1 is a bonding material 1 such as Ag paste.
9 to the heat spreader 2 and the insulating bonding material 20
It is joined to the inner lead 16. As the bonding material 20, a double-sided tape having an adhesive on both sides of an insulating tape is used. Also, on the side opposite to the semiconductor chip 1,
Wearing the 6 Heat spreader 2, except that the bottom surface is exposed, may be enclosed within a tree fat 18. Or it may be joined to the lower side of the semi-conductor chip 1. Further, as shown in FIG. 2, the heat spreader 2 has a Si spray coating 5. The inner lead 16 is preferably made of a Fe-Ni alloy having a low coefficient of thermal expansion.

[0009] In addition, the heat spreader 2 Ru can be formed of the various shapes. That is, the one provided with the pedestal 22 for supporting the inner lead 16 (see FIG. 2),
The semiconductor chip 1 is thinned by joining the semiconductor chip 1 in a recess provided in the heat spreader, and the thermally sprayed coating is also formed on the exposed lower surface of the heat spreader. In addition, the semiconductor chip and inner leads are TAB (Tape Au-to) without using bonding wires.
those that have been adopted heat spreader of the present invention to those connected by mated Bonding), also a plurality of semiconductor chips 1
May I der those multi-type equipped, the Cu-based metal 4 to the heat spreader of the mounting position of the chip is embedded. For this type of connecting device, a printed and printed FPC (Flexible Printed Curcuit) tape is used.
It is used and a bonding wire is connected to it. Note that a TAB tape or the like can be used instead of the FPC.

As described above, in the semiconductor device of the present invention, since the heat spreader 2 is composed of the composite of the Fe-based metal 3 and the Cu-based metal 4, the composition and ratio of the composite of both metals are adjusted. The thermal expansion coefficient of the heat spreader 2 can be approximated to the thermal expansion coefficient of the resin 18. That is, the resin 18 is made of epoxy resin or the like and has a thermal expansion coefficient of 12 to 15 × 10 ⁻⁶ / ° C., whereas Fe has a thermal expansion coefficient of 11.75 × 10 ⁻⁶ / ° C. and C.
Since u is 17 × 10 ⁻⁶ / ° C., the heat spreader 2 having a thermal expansion coefficient similar to that of the resin 18 can be formed by a composite of both metals or an alloy mainly containing both metals. Therefore, the heat spreader 2 and the resin 18
Adhesive deterioration due to the difference in thermal expansion is prevented, and at the time of reflow treatment and practical use, peeling of the boundary with the resin and generation of cracks are prevented. Further, since the heat spreader 2 is formed by vertically penetrating the Cu-based metal 4 having a high thermal conductivity, the heat spreader 2 can effectively radiate the heat of the semiconductor chip 1.

As the Fe-based metal 3 constituting the heat spreader 2, Fe (generally referred to as pure iron, carbon steel such as mild steel, etc., hereinafter referred to as Fe), and Fe-35 called amber.
˜37% Ni alloy, and Fe—Ni alloy such as Fe—42% Ni alloy (42Ni alloy) generally used for lead frames can be adopted. As the Cu-based metal 4, Cu and the thermal conductivity of Cu are 393 W / mK.
It is preferable to use a Cu alloy having a good thermal conductivity of about ± 10%. When an Fe-Ni alloy is adopted as the Fe-based metal 3, no deformation is observed after adhesion with the inner lead 16 made of the Fe-Ni alloy, which is good. The inner lead made of Fe-Ni alloy has excellent strength and is suitable for a multi-pin structure.

[0012] In the semiconductor device of the present invention, since the heat spreader 2 has a Si thermally sprayed film 5 as shown in FIG. 2, excellent adhesion to the resin 18, the cracks of the resin 18 at the time of the reflow process and practical Occurrence can be prevented. This is because Si or silicon oxide which may be formed on the surface thereof is well compatible with the resin 18, and the Si spray coating 5 has a surface roughness peculiar to the spray coating. It is thought that.
Further, the Si sprayed coating 5 has good adhesiveness with Ag paste or the like, and there is no problem when it is bonded to the semiconductor chip 1 .

Furthermore, in the semiconductor device of the present invention,
As shown in 1 or 3, the Cu-based metal 4 of the heat spreader 2, on the opposite side of the semiconductor chip 1, the heat radiation fins 6 that are mounted exposed. The heat radiation of the semiconductor chip 1 can be more effectively radiated by the heat radiation fins 6 as described above. Further, those contact kelch <br/> over preparative spreader 2 to the semiconductor device of the present invention are enclosed in resin 18, a plurality of belt-shaped bodies Cu-based metal 4 is deployed to the left and right, sand
When showing a KazuSatoshi example, those of the zebra structure as shown in FIG. 7
Good. In structures like this, the heat the semiconductor chip 1, is conducted transversely primarily through the strip-shaped Cu-based metal 4 of the heat spreader 2, since heat is radiated to the outside through the inner lead 16, the heat dissipation effect Are better.

[0014] Next, an example of a heat spreader employing the present invention will be described with reference to FIGS. 2 to 4. Figure 2
A plurality of Cu-based metals 4 are vertically penetrated and embedded in a plate-shaped block made of Fe-based metal 3. A pedestal 22 for supporting inner leads is provided, and a Si sprayed coating 5 is applied. Has been done. 4 (a) is intended to core 10 is embedded in the frame 11, Yes likewise cradle 22 is provided as FIG. 2, Si thermally sprayed film 5 is applied. Core 10, the semiconductor chip mounting position is buried through vertically as shown in FIG. 4 (b), the plurality of Fe-based metal 3 and a plurality of Cu-based metal 4 as shown in FIG. 4 (c) , Zn alloy and S
They are bonded to each other with a low melting point metal such as an n alloy. This heat spreader can be manufactured by fitting the core 10 into the frame body 11. Moreover, the wires of both metals 3 and 4 are mixed and inserted into the holes of the Fe-based metal billet to insert the low melting point metal. It can also be manufactured by cutting the cast product into slices.
Heat spreader shown in FIG. 4 (b), the groove 12 of the multiple-thread is provided on the side surface. Providing multiple grooves 12 on the side surface further improves the adhesion to the resin 18. The groove 12 may be provided on all four surfaces of the square column heat spreader, or may be provided on part of the surface. Such a grooved heat spreader is, as shown in FIG. 5 (a) or FIG. 5 (b),
The groove 12 is previously formed on the side surface of the bar 13 by cutting or the like.
Can be provided, and can be manufactured by cutting it in a line at the cutting line 14.

Figure6The other of the heat spreader of the present invention
Figure 2 shows a plan view and central cross section of an example. Figure6
(A) shows a cylindrical Cu30 in the center of a flat Fe31
Figure that is embedded vertically through the section6(B) is cylindrical
A plurality of Cu30 are similarly buried. Figure6
(C) Inserts Cu30 into a pipe of Fe-Ni alloy 32
Was embedded vertically through Fe31 in the form of a plate.
It is a thing. Figure6(D) is a large number of cylindrical Cu30 and
And a Fe-Ni alloy 32 with a low melting point Zn alloy 29.
The core 10 bonded to the
It is buried through the bottom. Figure6(E) is Cu30
Was inserted into a pipe of Fe-Ni alloy 32,
The cores 10 joined together with a Zn alloy 29 are embedded in the same manner.
It was set up. Figure7The present invention heat spreader
FIG. 6 is a perspective view of another example of Cu30, in which the Cu30 expands left and
A number of strips, alternating with Fe31 in planar layers.
It has a zebra structure. Figure7(A) is one Zeb
La structure and figure7(B) Two layers of zebra structure with each layer
It is laminated and crimped so as to be orthogonal to each other. Figure7(A)
Although there is anisotropy in thermal expansion and heat conduction,7
In (b), it has been improved.

[0016] In FIG. 6 (b) ~ (e) and 7, the coating layer 33 is provided on a surface to be bonded to the semiconductor chip. The coating layer 33 is formed by plating a metal having a good thermal conductivity such as Cu by plating or vapor deposition, and can conduct the heat of the semiconductor chip to a plurality of Cu-based metals to effectively dissipate the heat. The coating layer 33, FIG. 6
And Figure 4 may be provided on the inner side of the Si thermally sprayed film 5 of the heat spreader of (a). Also in the heat spreader 6 and 7, can be provided with grooves 12 on the side surface as shown in FIG. 4 (b), the may be provided cradle 22 as shown in FIG. In the example of FIGS. 6 and 7 , F
e can be replaced with a Fe-Ni alloy, and Fe-Ni alloy can be replaced with Fe. Cu can be replaced with the Cu alloy having a good thermal conductivity of about 393 W / mK ± 10% as described above. In addition, FIG. 6
In (d) and (e), the Zn alloy 29 can be replaced with a low melting point alloy such as a Sn alloy.

Since the heat spreader of the present invention is composed of a composite of Fe-based metal 3 and Cu-based metal 4, as described above, the thermal expansion can be achieved by adjusting the composition and ratio of the composite of both metals. The coefficient can be approximated to the coefficient of thermal expansion of the resin, preventing adhesion deterioration due to the difference in thermal expansion with the resin, and preventing peeling of the boundary with the resin and the occurrence of cracks during reflow processing and during practical use. . Moreover, since the Cu-based metal 4 having a high thermal conductivity is vertically penetrated to form a composite, the heat of the semiconductor chip 1 can be effectively radiated.

As shown in the examples of FIGS. 2 and 4 (a), the various heat spreaders of the present invention described above are provided with the Si thermal spray coating 5, so that the adhesion with the resin is further improved. The Si sprayed coating 5 may be on both surfaces of the heat spreader, or may be on only the surface on the semiconductor chip side or the surface on the opposite side. The thickness of the film is preferably 1 to 30 μm. If it is less than 1 μm, sufficient adhesion may not be obtained, and if it exceeds 30 μm, the effect is saturated. S
The i sprayed coating 5 can be formed in the atmosphere by a normal spraying method. In the case of partial thermal spraying, it suffices to shield the non-thermal spraying portion with a mask. According to thermal spraying
A thermal spray coating is formed around the end surface of the heat spreader. In addition, before spraying the heat spreader,
When preheated to a temperature of 0 to 300 ° C that does not oxidize, Si
A thermal spray coating is easily formed. Furthermore, the surface of the heat spreader before forming the Si sprayed coating is preferably roughened by sandblasting or the like, and the average roughness is preferably about 1 to 4 μm.

The various heat spreaders of the present invention are
As shown in FIGS. 1 and 3 , it has a radiation fin 6.
It Radiating fins 6, in FIG. 1, it extends a plurality of fins 8 in the vertical direction from the substrate 7, and extends laterally from post 9 in FIG. Both are bonded to the Cu-based metal 4 of the heat spreader 2 with the bonding material 21. As the material of the heat radiation fin 6, Cu, Al or the like having high thermal conductivity can be adopted. In yet heat spreader of the present invention, when provided with a cradle 22 as shown in FIG. 2 or FIG. 4 (a), when the film part of the cradle 22 to the insulator film such as Al ₂ O _3, only the adhesive Thus, the inner lead 16 can be joined. Further, the inner lead 16 can be joined by crimping.

[0020] As shown in FIG. 2 and FIG. 6 (a) ~ (c) ,
A heat spreader in which a cylindrical Cu-based metal is embedded in a plate-shaped block can be manufactured by punching a Fe-based metal formed into a desired shape and mounting the Cu-based metal in the hole by shrink fitting or the like. . Further, a billet made of Fe-based metal is longitudinally drilled, a Cu-based metal rod is inserted into the hole, and a work such as rolling is performed to make a small cross-section, which is cut into a ring and processed into a desired shape. You can also do it. Further, instead of the Cu-based metal cylinder, various shapes such as a prism can be adopted. Further, the process for producing the heat spreader having a core, that of Figure 4 is as defined above, FIG. 6
Also in (d) and (e), as in the case of FIG. 4 , a core 10 in which a plurality of various linear metals are joined to each other with a low melting point metal.
Can be fitted into the frame body 11 for manufacturing, and F
It is also possible to mix and insert various linear metals into the holes of the e-based metal billet, and cast the low melting point metal into slices to manufacture. In addition to these, rod-shaped Cu-based metals and Fe
Cu in a small-diameter pipe of system-based metal or Fe-Ni alloy
It is also possible to insert a rod material filled with a system metal into a relatively thick Fe pipe, subject it to hot extrusion, and then cut it into slices. In this case, it is not necessary to join with a low melting point alloy such as Zn alloy. A heat spreader having a zebra structure as shown in FIG. 7 is obtained by alternately stacking thin plates (disks, square plates, etc.) of Cu-based metal and Fe-based metal into a disk shape by pressure bonding with a hot isostatic press or the like. The plate obtained by rolling can be cut out by punching or the like to be manufactured.

[0021]

EXAMPLES As for various semiconductor devices, the materials for the heat spreader 2 and the inner lead 16 as shown in Table 1 were manufactured. No. of Table 1 3 is the apparatus of FIG. 3, and others are a comparative example and a conventional example without a radiation fin . In each of the heat spreaders of the present invention example and the comparative example , the ratio of the composite was adjusted so that the coefficient of thermal expansion approximated the coefficient of thermal expansion of the resin. As a result of observing the situation after the reflow treatment , No. 1, No. 2 and No. 4 was good overall. On the other hand , the present invention example No. 1 provided with a radiation fin. No. 3 had a very excellent heat dissipation property. Is <br/> et to the invention samples which were subjected to Si sprayed coating to heat over preparative spreader 2, adhesion to the resin was excellent. In Table 1, the insulating material adhesiveness is the deformation state after joining the heat spreader 2 and the inner lead 16 with the insulating material double-sided adhesive tape, and the die bonding strain is the strain after joining the heat spreader 2 and the semiconductor chip 1. Occurrence status and lead strength are strengths of the inner lead 16 and the outer lead 24, G is good, VG is very good, and NG
Indicates a defect.

[0022]

[Table 1]

[0023]

The resin-sealed semiconductor device of the present invention is made of Fe
It has a heat spreader made of a composite of a system metal and a Cu system metal, and the thermal expansion coefficient of the heat spreader can be adjusted to a value close to that of a resin. And heat spread
Since the thermal spray coating is applied to the drier, the adhesion between the heat spreader and the resin is excellent, the resin is prevented from cracking during reflow treatment and practical use, and it is also bonded to the semiconductor chip and the lead frame. It is also excellent in sex. In addition, the heat spreader dissipates heat
The fins are exposed and set, and the heat spreader is
It has excellent heat dissipation due with Cu-based metal formed, high-speed and large-capacity semiconductor device can be achieved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a semiconductor device of the present invention.

FIG. 2 is a cross-sectional view showing an example of a heat spreader adopted in the present invention.

FIG. 3 is a cross-sectional view showing another example of the semiconductor device of the present invention.

FIG. 4A is a sectional view showing another example of the heat spreader adopted in the present invention. (B) is a perspective view showing another example of the heat spreader adopted in the present invention.
(C) is a perspective view showing a core of the heat spreader adopted in the present invention.

5 (a) and 5 (b) are perspective views showing materials of a heat spreader adopted in the present invention.

6 (a) to 6 (e) are a plan view and a cross-sectional view showing another example of the heat spreader used in the present invention.

FIG. 7 is a cross-sectional view showing another example of the heat spreader adopted in the present invention.

FIG. 8 is a sectional view showing an example of a conventional semiconductor device.

[Explanation of symbols]

1: Semiconductor chip 2: Heat spreader 3: Fe-based metal 4: Cu-based metal 5: Si thermal spray coating 6: Radiation fin 7: substrate 8: Fin 9: Support 10: Core 11: frame 12: groove 13: Bar 14: Cutting line 16: Inner lead 17: Bonding wire 18: Resin 19, 20, 21: Joining material 22: Stand 23: Recess 24: Outer lead 25: Solder 26: Circuit board 27: Crack 29: Zn alloy 30: Cu 31: Fe 32: Fe-Ni alloy 33: coating layer

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-4-286147 (JP, A) JP-A-2-82645 (JP, A) JP-A-4-124860 (JP, A) JP-A-4- 6860 (JP, A) JP-A-3-231445 (JP, A) Actually developed 58-89930 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 23/28 H01L 23 / 29

Claims (2)

(57) [Claims] 1. In a semiconductor chip, a heat spreader mounting the semiconductor chip, and a resin-sealed semiconductor device in which inner leads connected to the semiconductor chip are sealed with resin, the heat spreader is made of Fe-based metal and Cu-based metal. The Cu-based metal is vertically penetrated and embedded, and has a Si thermal spray coating on the periphery, and the heat radiation fin is exposed to the heat spreader on the opposite side of the semiconductor chip. A semiconductor device that is mounted. 2. A heat spreader enclosed in resin,
The semiconductor device according to claim 1, wherein the Cu-based metal forming the heat spreader is composed of a plurality of strip-shaped bodies that expand left and right.