Semiconductor device

According to one embodiment, a semiconductor device includes a first semiconductor chip, a heat dissipation member provided on one surface of the first semiconductor chip and connected to the first semiconductor chip, and a sealing resin sealing the first semiconductor chip and the heat dissipation member. The heat dissipation member includes mutually interlaced metal fibers and a thermosetting resin.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2018-053249, filed on Mar. 20, 2018; the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described later relate generally to a semiconductor device.

BACKGROUND

Function and performance of a semiconductor device is remarkably improved, and increases of the output current and the output voltage are progressed. Thus, thermal loss of the semiconductor device also tends to increase. In such a semiconductor device, it is necessary to improve the heat dissipation performance of the package.

DETAILED DESCRIPTION

According to one embodiment, a semiconductor device includes a first semiconductor chip, a heat dissipation member provided on one surface of the first semiconductor chip and connected to the first semiconductor chip, and a sealing resin sealing the first semiconductor chip and the heat dissipation member. The heat dissipation member includes mutually interlaced metal fibers and a thermosetting resin.

The drawings are schematic and conceptual; and the relationships between the thickness and width of portions, the proportions of sizes among portions, etc., are not necessarily the same as the actual values thereof. Further, the dimensions and proportions may be illustrated differently among drawings, even for identical portions.

In the specification and drawings, components similar to those described or illustrated in a drawing thereinabove are marked with like reference numerals, and a detailed description is omitted as appropriate.

First Embodiment

FIG. 1Ais a bottom view illustrating a semiconductor device according to an embodiment.FIG. 1Bis a cross sectional view at AA line ofFIG. 1A.

As shown inFIG. 1AandFIG. 1B, a semiconductor device10of the embodiment includes a semiconductor chip11, a heat spreader12, and a sealing resin18. The semiconductor device10further includes a dummy chip13, a joining member14, a substrate15, a bonding wire16, and a connection terminal17. The semiconductor device of this example is a BGA package (Ball Grid Array) with the heat spreader. The package with the spreader is applicable not only to the BGA but also to an LGA (Land Grid Array), an SOP (Small Outline Package), a QFP (Quad Flat Package), a QFN (Quad For Non-lead Package), a DFN (Dual For Non-lead Package) or the like.

In the following, a plane including an X-axis and a Y-axis perpendicular to the X-axis is assumed to be generally parallel to a first surface11aof a semiconductor chip11. A Z-axis is perpendicular to the X-axis and the Y-axis. For example, a positive direction of the Z-axis is upward in the figure in a cross section shown below.

The heat spreader (heat dissipation member)12is provided generally parallel to the first surface11avia the dummy chip13on a side of the first surface11aof the semiconductor chip11. The first surface11ais one surface of the semiconductor chip11, and a surface where a connection pad connecting one end of a bonding wire16is provided.

The dummy chip13has no function, for example, is a chip formed of silicon (Si) or the like. The dummy chip13is provided parallel to the first surface11a. In an X-Y plan view, an area of the dummy chip13is set smaller than an area of the semiconductor chip11, and its perimeter is included in the perimeter of the first surface11a. The connection pad of the semiconductor chip11is provided to surround the outside of outer perimeter of the dummy chip13.

The dummy chip13is connected to the first surface11aof the semiconductor chip11by using an adhesive member13a. The dummy chip (spacer)13functions as a spacer when the bonding wire16connected to the first surface11ais formed in a loop shape so as to be convex in the positive direction of the Z-axis. The dummy chip13is provided in order to take a distance between the semiconductor chip11and the heat spreader12, and thus a loop portion of the bonding wire16does not contact the heat spreader12.

A semiconductor chip having a different function from the semiconductor chip11may be provided between the semiconductor chip11and the heat spreader12in place of the dummy chip13.

The heat spreader12is, for example, a generally square sheet member having an area not less than the area of the semiconductor chip11. The area of the heat spreader12is larger than, for example, the area or the semiconductor chip11in the X-Y plan view, and the perimeter of the heat spreader12includes all the perimeter of the semiconductor chip11.

The heat spreader12is made of a metal fiber sheet including a metal fiber including copper (Cu) or a Cu alloy and a thermosetting resin (hereinafter, referred to as simply metal fiber sheet). The metal fibers include mutually interlaced metal fibers having a high aspect ratio such as, for example, a fiber diameter of approximately 1 μm to 10 μm and a fiber length of approximately 1 mm to 10 mm. Mutually interlacing represents a state of metal fibers which get tangled one another. A content ratio of Cu in the metal fiber is favorably 100%, however the content of Cu may be less than 100%.

The thermosetting resin is impregnated into the metal fiber. The thermosetting resin is a resin which cures by heat, for example, a thermosetting adhesive, and is favorably conductive. The thermosetting adhesive can include a synthetic rubber and a natural rubber such as acrylonitrile-butadiene copolymer (NBR) or the like as a rubber component. An epoxy resin and a phenol resin or the like can be included. A cure temperature of the epoxy resin can be approximately 100° C. to approximately 160° C. Conductivity can be improved by using various metal powders or the like as conductive fillers.

The heat spreader12is the metal fiber sheet including the interlaced metal fibers impregnated thermosetting resin, and as described later, is formed by cutting the metal fiber sheet to a predetermined shape and size.

In this way, the heat spreader12includes the thermosetting resin. For that reason, the heat spreader12can be connected to the dummy chip13by heating after placing the heat spreader12on the dummy chip13.

The semiconductor chip11is connected to the substrate15via the joining member14. The joining member14is, for example, a silver (Ag) paste. A connection pad provided on the first surface11ais electrically connected to the connection pad on the substrate15via the bonding wire16. The connection pad on the substrate15is electrically connected to a connection terminal17by an interconnection provided on and inside the substrate15. The connection terminal17is, for example, a solder ball.

The semiconductor device10is sealed by the sealing resin18in order to protect an internal structure including the semiconductor chip11from an external environment. In this example, the sealing resin18seals the whole except a side surface and a lower surface of the substrate15, and the connection terminal17.

Effects of the semiconductor device10of the embodiment will be described while comparing with a semiconductor device of a comparative example.

FIG. 2is a cross section of a semiconductor device of a comparative example at a place corresponding to AA line ofFIG. 1A.

As shown inFIG. 2, a semiconductor device110of the comparative example includes the semiconductor chip11, a heat spreader112, and the sealing resin18. The heat spreader112is a sheet material made of Cu or a Cu alloy of bulk. In the case of the comparative example, the heat spreader112is connected onto the semiconductor chip11via the dummy chip13. The heat spreader112is connected to the dummy chip13via an adhesive member13b. The dummy chip13is connected to the semiconductor chip11via the adhesive member13a. That is, both sides of the dummy chip13are necessary to be coated with the adhesive members13a,13b. For example, in the case where an adhesive tape is used for adhesion, the adhesive tape is affixed to the both sides of the dummy chip13in advance.

In the case of the comparative example, the heat spreader112is necessary to be sufficiently adhered to the sealing resin18when filling the sealing resin18. For that reason, each side of the heat spreader112is, for example, necessary to be subjected to roughening treatment in advance.

On the contrary, in the semiconductor device10of the embodiment, since the heat spreader112includes the mutually interlaced metal fibers, the each side of the heat spreader12is substantially roughened by the mutually interlaced metal fibers. For that reason, the connection area with the sealing resin18increases and the adhesion is improved. Since peeling off of the heat spreader12from the sealing resin18is suppressed by a thermal stress in mounting the semiconductor device10on an apparatus or the like, reliability of environmental resistance can be improved.

Furthermore, in the semiconductor device10of the embodiment, since the connection surface of the heat spreader12and the sealing resin18is substantially roughened and the connection area with the sealing resin increases, a thermal resistance is reduced and the heat dissipation performance is improved.

In the semiconductor device10of the embodiment, since the heat spreader12includes the thermosetting resin, the heat spreader12can be connected to the dummy chip13by applying the heat treatment without providing the adhesive member separately. Therefore, it is possible to reduce the adhesive and the adhesive tape, and to reduce a portion of process of coating the adhesive on the both sides of the dummy chip13.

Since the heat spreader can be of any shape and thickness, the heat spreader can be designed depending on necessary heat dissipation performance. Changing the configuration of the heat spreader makes it possible to further reduce the member.

FIG. 3AtoFIG. 3Care cross sectional views illustrating the variation at the position corresponding to AA line ofFIG. 1A.

The configuration of the above embodiment can also be applied to GFN, DFN, QFP, SOP or the like with the heat spreader.FIG. 3AtoFIG. 3Care examples of applying to GFN (or DFN).

As shown inFIG. 3A, a semiconductor device10aincludes the semiconductor chip11, and the heat spreader12. The dummy chip13is provided between the semiconductor chip11and the heat spreader12, and the semiconductor chip11and the dummy chip13are connected by the adhesive member13asuch as an adhesive tape or the like. The heat spreader12is connected to the dummy chip13by the thermosetting resin impregnated into the heat spreader12. In this example, a side of the semiconductor chip11opposite to the first surface11ais connected to a die pad15avia, for example, the joining member14such as an Ag paste. An electrode pad on the semiconductor chip11is electrically connected to a connection terminal17aof a flat lead via the bonding wire16.

As shown inFIG. 3B, the dummy chip13may be replaced by a heat spreader12b. That is, a semiconductor device10bincludes the semiconductor chip11and the heat spreaders12,12b. The heat spreader (heat dissipation member)12bis provided between the semiconductor chip11and the heat spreader12. The heat spreader12bfunctions as a spacer which causes the bonding wire16not to contact the heat spreader12by taking a distance in the Z-axis direction between the semiconductor chip11and the heat spreader12. Both of the heat spreaders12,12bare made of the metal fiber sheet. The metal fiber sheet includes the thermosetting resin. Therefore, the heat spreader12breplaced from the dummy chip13can be connected to the first surface11aof the semiconductor chip11by performing a heat treatment without using the adhesive tape or the like.

Since the heat spreader12bincludes the metal fiber such as Cu or the like, the thermal conductivity is high compared with the dummy chip13of silicon (Si) or the like, the thermal resistance from the semiconductor chip11to the heat spreader12is reduced, and the heat dissipation performance is further improved.

As shown inFIG. 3C, in a semiconductor device10c, the dummy chip or the like is not provided and a heat spreader12cis connected directly onto the semiconductor chip11. The perimeter of a surface of the heat spreader (heat dissipation member)12cparallel to the X-Y plane is set to be included in the perimeter of the first surface11aof the semiconductor chip11. More specifically, the perimeter of the heat spreader12cis connected to the inside of the connection pad disposed on the first surface11a. An area of the surface of the heat spreader12cparallel to the X-Y plane is set to be smaller than the area of the semiconductor chip11.

The thickness of the heat spreader made of the metal fiber sheet can be set arbitrarily. For that reason, like this variation, the thickness of the heat spreader12ccan be approximately total thickness of the heat spreader and the dummy chip of the above embodiment and the variation. Therefore, the heat spreader12ccan be avoided from contacting the bonding wire16.

In this way, in the variation, the number of the components is possible to be reduced compared with the case of the comparative example. Like this variation, the thermal resistance of the heat spreader12ccan be reduced and the heat dissipation performance of the package can also be improved by increasing the thickness of the heat spreader12c.

In the above, in connecting the semiconductor chip11to the die pad15a, the joining member such as an Ag paste or the like may be replaced by the metal fiber sheet used for the heat spreader.

Second Embodiment

In the case of connecting the semiconductor chip to the die pad, the heat dissipation performance can be improved by using the metal fiber sheet impregnated with the thermosetting resin in place of using the joining member such as an Ag paste or the like between the semiconductor chip and the die pad.

FIG. 4is a cross sectional view illustrating a semiconductor device according to the embodiment at the position corresponding to AA line ofFIG. 1A.

As shown inFIG. 4, a semiconductor device210of the embodiment includes the semiconductor chip11, a joining member214, and the die pad15a. The joining member214is provided between the semiconductor chip11and the die pad15a. The semiconductor chip11is connected to the die pad15aat a back side (second surface)11bvia the joining member214.

The joining member (heat dissipation member)214includes the metal fiber sheet. Thermosetting resin is impregnated into the metal fiber sheet. The metal fiber sheet is configured as well as the heat spreaders of the above described other embodiments and the variations. That is, the metal fiber sheet includes the mutually interlaced metal fibers including Cu or a Cu alloy, and the thermosetting resin is impregnated.

Since the joining member214includes the metal fiber in the mutually interlaced state based on a high thermal conductivity metal material such as Cu or the like, the thermal conductivity is high and therefore the thermal resistance of the semiconductor device210can be small. Since the metal fiber does not include lead (Pb), the semiconductor device210can be a Pb free package. Since the thermosetting resin of the joining member214can be cured at a relatively low temperature, the thermal stress at manufacturing the semiconductor device210can be reduced, and the environmental resistance of the semiconductor device210can be improved.

FIG. 5AtoFIG. 5Eare cross sectional views illustrating a manufacturing process of the semiconductor device ofFIG. 4.

As shown inFIG. 5A, a lead frame15LF is prepared. The lead frame15LF includes a portion serving as the die pad15aand a portion serving as the connection terminal17.

As shown inFIG. 5B, the semiconductor chip11and the joining member214are individualized from a semiconductor wafer11WF affixed on a metal fiber sheet214SH. For example, the semiconductor wafer11WF is placed on the metal fiber sheet214SH, and is heated from a side of the semiconductor wafer11WF. This connects the metal fiber sheet214SH to the semiconductor wafer11WF. After that, the semiconductor chip11is cut and individualized in a state of the joining member214affixed to the back side.

The individualized semiconductor chip11and the joining member24are placed on a portion serving as the die pad of the lead frame15LF.

For example, the thickness of the joining member214is set to be approximately 100 μm, however the thicknesses of the metal fiber sheet214SH and the joining member214are not limited to this, and is set depending on the heat dissipation performance of the package.

As shown inFIG. 5C, the thermosetting resin is heated to the curing temperature of the thermosetting resin from the lead frame15LF side, and thus the semiconductor chip11is connected to the die pad portion of the lead frame15LF.

As shown inFIG. 5D, the connection pad of on the semiconductor chip11is connected to the portion serving as the connection terminal of the lead frame15LF via the bonding wire16.

As shown inFIG. 5E, the sealing resin is filled by a transfer mold or the like, and the lead frame15LF is cut.

FIG. 6is a cross sectional view illustrating a semiconductor device according to the variation at the position corresponding to AA line ofFIG. 1A.

As described in the case of the above described other embodiments, the thickness of the metal fiber sheet impregnated with the thermosetting resin can be set arbitrarily. In the second embodiment, the thermal resistance can be further reduced by thickening the thickness of the joining member formed by cutting the metal fiber sheet.

As shown inFIG. 6, a semiconductor device210aincludes a joining member214a. The joining member (heat dissipation member)214ais provided between the semiconductor chip11and the die pad15a. The joining member214ais cut from the metal fiber sheet having a sufficient thickness to be used. The thickness of the joining member214ais thicker than the thickness of the semiconductor chip11. A desired low thermal resistance (transient thermal resistance) can be realized by sufficiently increasing the thickness of the joining member214a. For example, the thickness of the joining member214acan be approximately 500 m.

An area of a surface parallel to the X-Y plane of the joining member214acan also be set arbitrarily. In this example, the area of the joining member214ais set to be larger than the area of the semiconductor chip11. Therefore, the thermal resistance of the joining member214acan be reduced, and the heat dissipation performance of the semiconductor device210acan be further improved.

FIG. 7AtoFIG. 7Eare cross sectional views illustrating a manufacturing process of the semiconductor device ofFIG. 6.

As shown inFIG. 7A, the lead frame15LF is prepared. This lead frame15LF may be the same as the lead frame15LF of the second embodiment.

As shown inFIG. 7B, the cut joining member214ais placed on a die pad portion of the lead framed15LF. The joining member214aand the lead frame15LF temporarily connect by heating. The temporal connection is referred to as temporal fixing for connecting the joining member214aand the lead frame15LF after the next process.

Here, as shown in the right figure ofFIG. 7B, the joining member214ais cut into a predetermined shape from a metal fiber sheet214aSH impregnated with the thermosetting resin. The metal fiber sheet214aSH is set to have a thickness (500 μm) approximately 5 times the thickness in the second embodiment. The area parallel to the X-Y plane is set to be larger than the area of the semiconductor chip11.

As shown inFIG. 7C, the semiconductor chip11is placed on the joining member214a, and the semiconductor chip11, the joining member214a, and the lead frame15LF are connected one another by heating.

As shown inFIG. 7D, the semiconductor chip11and the connection terminal17aare connected by the bonding wire16.

As shown inFIG. 7E, the resin is filled by the transfer mold or the like, and the lead frame15LF is cut.

In this way, in the variation, the thermal resistance of the package can be easily reduced by appropriately setting the thickness and the area of the joining member214a.

In this way, in the semiconductor devices210,210aof the embodiment and the variation, the number of main process can be five processes.

Effects of the semiconductor devices of the embodiment and the variation will be described while comparing with the semiconductor device of the comparative example.

FIG. 8AtoFIG. 8Dare cross sectional views of semiconductor devices of comparative examples at the position corresponding to AA line ofFIG. 1A.

As shown inFIG. 8A, a semiconductor device210sof the comparative example includes a joining member21sbetween the semiconductor chip11and the die pad15a. The joining member214sis a generally used joining member, and is an Ag paste or the like. The Ag paste has low thermal conductivity and thus the thermal resistance of the semiconductor device210sincreases and the heat dissipation performance is low.

As shown inFIG. 8B, the semiconductor device210sincludes a metal plate211s. The metal plate211shaving high thermal conductivity such as Cu or the like is provided between the semiconductor chip11and the die pad15a. The metal plate211sis connected to the semiconductor chip11via a joining member214us, and connected to the die pad15avia a joining member214bs.

The metal plate211sfunctions as a heat spreader. That is, the heat dissipation of the semiconductor device210s1is improved by adding the metal plate211shaving the low thermal resistance to a conduction path of the heat.

As shown inFIG. 8C, a semiconductor device210s2includes a joining member214sh. In the joining member214shof this comparative example, the thermal resistance of the joining member214shis reduced by increasing a content of heat conduction particle in the joining member, for example, an Ag particle.

As shown inFIG. 8D, a semiconductor device210s3includes a joining member214ss. The thermal conductivity of the joining member214ssis improved and the thermal resistance is reduced by subjecting the heat conduction particle such as the Ag particle or the like to a sintering treatment (sintering).

A high temperature heat treatment is necessary for the joining members such as the joining member214sh,214sshaving a high thermal conductivity in a connection processing with the semiconductor chip and the die pad.

FIG. 9AtoFIG. 9Gare cross sectional views showing an outline of a manufacturing process of the semiconductor device ofFIG. 8Bat the position corresponding to AA line ofFIG. 1A.

As shown inFIG. 9A, the lead frame15LF is prepared, and as shown inFIG. 9B, the joining member214bsis coated to the die pad portion of the lead frame15LF.

As shown inFIG. 9C, a metal plate211sis placed on the joining member214bs, and as shown inFIG. 9D, the joining member214usis coated onto the metal plate211s.

As shown inFIG. 9E, the semiconductor chip11is placed on the joining member214us.

As shown inFIG. 9F, the semiconductor chip11and the portion serving as the connection terminal are connected by the bonding wire16.

As shown inFIG. 9G, the resin is filled by the transfer mold or the like, and the lead frame15LF is cut.

In this way, in the case of the package with the metal plate211sfor decreasing the thermal resistance, the number of processes increases by addition of the metal plate211s, and the main processes are formed of seven processes.

FIG. 10AtoFIG. 10Fare cross sectional views showing a manufacturing flow of the semiconductor device ofFIG. 8Dat the position corresponding to AA line ofFIG. 1A.

As shown inFIG. 10A, the lead frame15LF is prepared, and as shown inFIG. 10B, a joining member214ss1is coated to the die pad portion of the lead frame15LF.

As shown inFIG. 10C, after the semiconductor chip11is placed on the joining member214ss1, as shown inFIG. 10D, the sintering treatment for decreasing the thermal resistance is performed, and the joining member214sshaving the improved thermal conductivity is obtained. The sintering treatment is a long time high temperature curing treatment, for example, it is performed at approximately 250° C. and for 90 minutes in the case of the Ag paste.

As shown inFIG. 10E, the semiconductor chip11and the portion serving as the connection terminal are connected by the bonding wire16, and as shown inFIG. 10F, the resin is filled by the transfer mold or the like, and the lead frame15LF is cut.

In this way, in the case of the comparative example, since the sintering treatment of the Ag paste is added for decreasing the thermal resistance, the number of the main processes is six. The high temperature heat treatment is required for the sintering treatment of the Ag paste, and throughput of the manufacturing decreases.

On the contrary, in the embodiment and its variation, the number of the main processes can be reduced to 5 by using the joining member214made of the metal fiber sheet. Because of the decrease of the thermal resistance, the manufacturing process can be more shortened than the case of the comparative example which requires 6 processes or 7 processes.

In the semiconductor device of the embodiment and the variation, the joining member214is formed of the metal fiber sheet. For that reason, the decrease of the thermal resistance can be easily realized by the high thermal conductivity of the metal fiber. A desired value of the thermal resistance can also be easily realized by setting adequately the area and the thickness of the joining member214.

Since the metal fiber of the joining member214does not include Pb, the semiconductor devices210,210acan be Pb free.

The joining member214includes a thermosetting resin. Since the thermosetting resin has low temperature curing characteristics, the semiconductor chip11and the die pad15acan be connected by the short time heat treatment. Therefore, the thermal stress in manufacturing the semiconductor device can be reduced and the environmental resistance can be improved.

Third Embodiment

The metal fiber sheet impregnated with the thermosetting resin can also be used as the die pad or the connection terminal by forming into a lead frame configuration.

FIG. 11Ais a cross sectional view of a semiconductor device according to the embodiment at the position corresponding to AA line ofFIG. 1A.FIG. 11Bis a cross sectional view of a semiconductor device of a comparative example at the position corresponding to AA line ofFIG. 1A.

As shown inFIG. 11A, a semiconductor device310includes the semiconductor chip11and a die pad315. The semiconductor chip11is connected onto the die pad315. The die pad315is formed by disconnecting the lead frame cut from the metal sheet impregnated with the thermosetting resin with a connection terminal317.

The die pad315includes the metal fiber, and thus has low thermal resistance. A desired low thermal resistance value can be realized by adjusting a thickness of the die pad315.

The die pad315includes the thermosetting resin, and thus can be connected to the semiconductor chip11without use of the joining member and without the long time heat treatment. Since the metal fiber does not include Pb, the semiconductor device310can be Pb free.

Furthermore, the surfaces of the die pad315and the connection terminal317are substantially roughened by the metal fiber, and adhesion with the sealing resin18can be improved. The adhesion of the die pad317and the connection terminal317with the sealing resin18is improved, and thus it is difficult for troubles such as peeling to be caused by thermal stress or the like during mounting to the device, and the environmental resistance can be improved.

As shown inFIG. 11B, in the semiconductor device310of the comparative example, the semiconductor chip11is connected onto a die pad315sincluding Cu via the joining member314s, for example. In the case where the joining member314sis the Ag paste or the like, the thermal resistance is low and the heat dissipation performance of the semiconductor device310sis low. Although the thermal resistance can be improved by changing the Ag paste to solder or the like, it may be difficult to make Pb free.

In the semiconductor device310sof the comparative example, the die pad315sand the connection terminal317shave notches315bs,317bs. The notches315bs,317bsare provided across the respective perimeters on a lower surface side of the die pad315sand the connection terminal317s, namely, on a side of a surface opposite to the surface where the semiconductor chip11is mounted. When the sealing resin is filled, the sealing resin18wraps around the notches315bs,317bs, and thus the adhesion of the die pad315sand the connection terminal317swith the sealing resin18is improved. The improvement of the adhesion of the die pad315sand the connection terminal317swith the sealing resin18prevents the die pad315sand the connection terminal317sfrom dropping off from the sealing resin18.

However, since the notches315bs,317bslike this are formed by etching the lead frame, it takes a processing time and becomes a factor of increasing the cost.

In the semiconductor device310of the embodiment, since the die pad315and the connection terminal317are formed of the metal fiber sheet, surfaces of the die pad315and the connection terminal317are substantially roughened by the metal fiber, and the adhesion with the sealing resin is improved. Therefore, the semiconductor device310having high adhesion with the sealing resin can be realized without subjecting the metal fiber sheet to special processing.

The die pad315can be connected to the semiconductor chip11by the thermosetting resin impregnated with the metal fiber without via the joining member. Therefore, the manufacturing process of the semiconductor device310can be more simplified than the case of the comparative example.

FIG. 12Ais a partial cross sectional view of a semiconductor device according to the variation at the position corresponding to AA line ofFIG. 1A.FIG. 12Bis a cross sectional view of a semiconductor device of a comparative example at the position corresponding to AA line ofFIG. 1A.

In this variation, the metal fiber sheet impregnated with the thermosetting resin is provided in portions of the die pad and the connection terminal.

As shown inFIG. 12A, a semiconductor device310aof the variation includes a die pad315a, a connection terminal317a, and the sealing resin18. Plated layers315b,317bare provided on surfaces of the die pad315aand the connection terminal317a, respectively. A metal fiber layer319is provided between the plated layer315bof the die pad315aand the sealing resin18. The metal fiber layer319is provided also between the plated layer317bof the die pad315aand the sealing resin18. The metal fiber layer319is a layer of the metal fiber sheet impregnated with the thermosetting resin.

In the variation, in order to obtain sufficient adhesion of the sealing resin18with the die pad315aincluding the plated layer315band the connection terminal317aincluding the plated layer317b, the metal fiber layer319is provided in these connection portions. The metal fiber layer319is not provided in an exposed portion of the connection terminal317afor connecting an external circuit.

The plated layers317bof nickel (Ni), palladium (Pd) and gold (Au) are stacked in this order on the portion exposed to the outside of the connection terminal317afrom the surface side of the base material, for example. The highly stable plated layers315b,317bare formed, and thus a connection state with high reliability can be realized even if in the external environment including solder flux or the like.

The metal fiber layer319is selectively affixed to the connection portion to the sealing resin in advance on the surfaces of the die pad315aand the connection terminal317a, for example. The metal fiber layer319is not affixed to the portion exposed to the outside of the connection terminal317a, and the metal plated layer of Au or the like is exposed.

As shown inFIG. 12B, in a semiconductor device310saof the comparative example, for example, multilayered plating of Ni, Pd, Au is formed in the initial stage on the whole surface of the die pad315aand the connection terminal317a, however the portion connected to the sealing resin18is roughened until the approximately Ni layer in order to secure the adhesion with the sealing resin. For that reason, it results in formation of the roughened plated layers315c,317con the surfaces of the die pad315aand the connection terminal317a. Although the adhesion is ensured by the roughened plated layers315cand317cin the connection portion to the sealing resin18, the plated layer317cof the exposed surface of the connection terminal317ais also roughened, and thus degradation of connection strength and solder wettability or the like may occur by long-term exposure to the external environment.

In the variation, by selectively providing the metal fiber layer319, the die pad315aand the connection terminal317acan maintain the plated layer317bfor external connection while securing the adhesion with the sealing resin18.

For that reason, the die pad315aand the connection terminal317ado not peel off from the sealing resin18due to the thermal stress in substrate mounting or the like for connecting to the external circuit, and the environmental resistance can be improved. The heat conduction to the sealing resin18is improved by enlarging the connection area of the sealing resin with the die pad315aand the connection terminal317a, and the heat conduction improvement is expected to contribute to the improvement of the thermal resistance.

The highly stable plated layer317bis exposed to the surface of the connection terminal317aexposed to the outside, and the connection terminal317acan be connected to a connection land or the like formed on the substrate of the external circuit by the plater layer317bwith high reliability.

Fourth Embodiment

If the metal fiber sheet is affixed to an externally exposed electrode of a semiconductor device, the thermal resistance during substrate mounting can be reduced.

FIG. 13Ais a bottom view illustrating a semiconductor device according to the embodiment.FIG. 13BandFIG. 13Care cross sectional views at BB line ofFIG. 13A.

FIG. 13BandFIG. 13Cshow a substrate430mounting a semiconductor device410together with the semiconductor device410.

As shown inFIG. 13AtoFIG. 13C, an additional exposed electrode411is provided on the bottom surface of the semiconductor device410. The additional exposed electrode (heat dissipation member)411is affixed to an exposed surface of an exposed electrode415serving as the die pad. The additional exposed electrode411is provided so that the perimeter surrounds the perimeter of the exposed electrode415. The area of the addition exposed electrode411is set to be larger than the area parallel to the X-Y plane of the exposed electrode415.

The semiconductor chip11is provided on the exposed electrode415via a joining member414. The joining member414may be, for example, either solder or the metal fiber sheet.

The semiconductor device410can be connected to the external circuit by an interconnection pattern432drawn on the substrate430. The substrate430is a PCB (Printed Circuit Board), and a heat dissipation pattern431is provided on the substrate430other than the interconnection pattern432. The heat dissipation pattern431has a larger area than the interconnection pattern432. The heat dissipation pattern431may be connected to one or more of the interconnection patterns432on any position of the substrate430.

The substrate430is formed of an insulating material such as, for example, polyimide-based resin, glass epoxy, various ceramics or the like. The heat dissipation pattern431and the interconnection pattern432are good conductors such as Cu or the like, which are formed by etching or the like on the substrate430or in the substrate430.

The heat dissipation pattern of this example is provided to fit a perimeter shape and the area of the additional exposed electrode411. The land is provided on the interconnection pattern432, and a spare solder433is made on the land.

The additional exposed electrode411is directly connected to the heat dissipation pattern431of the semiconductor device410, and is connected to the connection terminal417.

Effects of the semiconductor device of the embodiment will be described while comparing with to semiconductor device of a comparative example.

FIG. 14Ais a bottom view illustrating the semiconductor device of the comparative example.FIG. 14BandFIG. 14Care cross sectional views at CC line ofFIG. 14A.

As shown inFIG. 14AtoFIG. 14C, a semiconductor device410sof the comparative example includes the exposed electrode415which is exposed to the outside. The semiconductor chip11is provided on the exposed electrode415via the joining member414.

A heat dissipation pattern431sand the interconnection pattern432are provided on a substrate430s. The spare solder433is made on both the heat dissipation pattern431sand the interconnection pattern432.

The exposed electrode415and the connection terminal417of the semiconductor device410sare connected to the heat dissipation pattern431sand the interconnection pattern432, respectively via the solder433. The solder433can spreads a bit depending on the wettability, however is difficult to spread so as to broaden the heat dissipation path sufficiently. Therefore, since an area of the heat dissipation pattern431scannot be broadened sufficiently more than an area of the exposed electrode415, improvement of heat dissipation due to enlargement of the heat dissipation pattern431sis not said to be sufficient in the semiconductor device410of the comparative example.

On the contrary, in the case of the embodiment, the additional electrode411is provided between the exposed electrode415and the heat dissipation pattern431, and the perimeter shape and the area of the additional exposed electrode411can be sufficiently larger than the exposed electrode415. Since the additional exposed electrode411is made of the metal fiber sheet and has high thermal conductivity, the low thermal resistance can be realized in the semiconductor device410mounted on the substrate430. Therefore, in the case where the semiconductor device410is mounted on the substrate430, the perimeter shape and the area of the heat dissipation pattern431can be larger than the exposed electrode415, and the heat dissipation performance of the semiconductor device410during mounting can be improved.

FIG. 15Ais a front view illustrating a semiconductor device according to the variation.FIG. 15Bis a side view illustrating the semiconductor device according to the variation.

The semiconductor device including the exposed electrode can be applied to a package of insert type such as SIP (Single Inline Package) and ZIP (Zigzag Inline Package) or the like without limitation to a surface mounting package.

As shown inFIG. 15AandFIG. 15B, a semiconductor device410aincludes a main body410a1and an additional heat dissipation fin411a. The additional heat dissipation fin411ais affixed to a heat dissipation fin415aserving as the die pad. The perimeter of the additional heat dissipation fin411aincludes the perimeter of the heat dissipation fin415a, and an area of the additional heat dissipation fin411ais larger than an area of the heat dissipation fin415a. The additional heat dissipation fin411ais provided between the heat dissipation fin415aand an wall surface440aof a housing440when mounting the main body.

The additional heat dissipation fin (heat dissipation member)411ais made of the metal fiber sheet. The additional heat dissipation fin411ais connected to the heat dissipation fin415aof the main body410a1by the thermosetting resin of the metal fiber sheet.

The semiconductor device410ais connected to the wall surface440aby the thermosetting resin of the additional heat dissipation fin411a. In order to increase the connection strength at oscillation, the semiconductor device410amay be tightened and fixed by a bolt and a nut or the like piercing, for example, the main body410a1, the additional heat dissipation fin411aand the housing440.

A connection terminal417aof the semiconductor device410ais inserted into the land hole of the substrate430, and is soldered.

The additional heat dissipation fin itself may be used as the wall surface of the housing440.

In this way, even in the case of a self-contained mounting type semiconductor device, the thermal resistance of the semiconductor device410acan be reduced and the heat dissipation performance can be improved by providing the additional heat dissipation fin411abetween the heat dissipation fin415aof the main body and the wall surface440a.

In the case where screw rock of the semiconductor device410ato the wall surface440acan be omitted, the semiconductor device410acan be easily attached to the housing440by heating the thermosetting resin of the additional heat dissipation fin411a.

Fifth Embodiment

FIG. 16Ais a plan view illustrating a semiconductor device according to a fifth embodiment.FIG. 16Bis a cross sectional view at DD line ofFIG. 16A.

As shown inFIG. 16AandFIG. 16B, a semiconductor device510of the embodiment includes the semiconductor chip11and an interconnection member516. The semiconductor device510further includes a die pad515and connection terminals517a,517b.

The interconnection member516is made of the metal fiber sheet impregnated with the thermosetting resin. One end516t1of the interconnection member516is connected to the connection pad of the semiconductor chip11. The interconnection member516is bent in the negative direction of the Z-axis between the one end516t1and other end516t2. The other end516t2of the interconnection member516is connected to the connection terminal517a. Lower surfaces of the die pad515and the connection terminals517are included in the same plane. The semiconductor chip11is connected to the die pad515on an opposite surface (second surface11b) of the first surface11avia a joining member514. The joining member514is made of the metal fiber sheet impregnated with the thermosetting resin.

Other connection pad of the semiconductor chip11is electrically connected to the connection terminal517bvia the bonding wire16.

The semiconductor chip11is a discrete element including a back side electrode such as, for example, MOFET (Metal-Oxide-Semiconductor Field-Effect Transistor). When the semiconductor chip11is MOSFET, the die pad515is a drain electrode, and the connection terminal517ais a source terminal, and the connection terminal517bis a gate terminal.

Since the interconnection member516of the semiconductor device510of the embodiment includes the thermosetting resin, heat crimp can be made at a low temperature without requiring a high temperature solder joining process for connection of the semiconductor chip11and the connection terminal517a.

Since the interconnection member516includes the metal fiber, high conductivity can be realized and low loss of the semiconductor device510is possible.

Since the surface of the interconnection member516is substantially roughened by the metal fiber, the environmental resistance and the heat dissipation performance can be improved by improvement of the adhesion with the sealing resin18.

Since the joining member514made of the metal fiber sheet is also used for connection of the semiconductor chip11and the die pad515, package assembling is possible at a low temperature. For that reason, the manufacturing line can be simplified in the semiconductor device510.

Since solder and Pb are not used in manufacturing the semiconductor device510, Pb free can be made easily.

FIG. 17Ais a perspective view illustrating a semiconductor device according to the variation.FIG. 17Bis a cross sectional view at EE line ofFIG. 17A.

FIG. 17Aschematically show by abstracting the portion of the sealing resin.

As shown inFIG. 17AandFIG. 17B, the multiple interconnection members516are used in parallel in a semiconductor device510aof the variation. The semiconductor chip11is connected to the die pad515by the joining member514. The joining member514is, for example, the solder and the metal fiber sheet. Each interconnection member526ais connected to the connection pad on the semiconductor chip11at one end516at1and connected to the connection terminal517aat other end516at2.

The interconnection member516ais made of the metal fiber sheet impregnated with the thermosetting resin. A direct current resistance value between the semiconductor chip11and the connection terminal517acan be reduced by the multiple interconnection members516a. For that reason, an outputting current of the semiconductor device510ais increased, and a power loss can be reduced.

Since the interconnection member516aincludes the thermosetting resin as well as the case of the other embodiments described above, the semiconductor chip11and the connection terminal517acan be connected at a low temperature heat treatment. For that reason, the thermal stress in the manufacturing can be reduced and the environmental resistance of the semiconductor device510acan be improved.

FIG. 18Ais a bottom view illustrating a semiconductor device according to the variation.FIG. 18Bis a cross sectional view at FF line ofFIG. 18A.

As shown inFIG. 18aandFIG. 18B, the semiconductor device510bof the variation includes the semiconductor chip11and multiple interconnection members516b. The first surface11aof the interconnection members516bare directed downward, namely, to the negative direction of the Z-axis. The interconnection members516bare connected to the first surface11aat one end516bt1. As described later, other end516bt2functions as the connection terminal to the external circuit. The number of the interconnection members516bis favorable to be multiple not less than 3, for example. The interconnection members516bmay be provided to surround the perimeter portion of the first surface11alike this example.

The interconnection members516bare connected to the connection pad on the first surface11aat the one end516bt1and are bent toward the negative direction of the Z-axis between the one end516bt1and the other end516bt2. Bottom surfaces of the other ends516bt2of the all interconnection members516bare included in the same plane parallel to the XY plane.

The interconnection members516bare made of the metal fiber sheet impregnated with the thermosetting resin. The one end516bt1is connected to the connection pad provided on the first surface11aby the heat treatment.

The other end516bt2is connected by the heat treatment to the land of the interconnection pattern531provided on the substrate530for connecting to the external circuit.

The semiconductor device510bof the embodiment includes multiple number s of interconnection members516bmade of the metal fiber sheet. The multiple number s of interconnection members516bare connected to the semiconductor chip11at the one end516bt1, and connected to the substrate at the other ends516bt2. Therefore, the interconnection member516forms a heat dissipation path from the semiconductor chip11, and the heat can be effectively dissipated to the substrate530.

The interconnection member516can be easily connected to the semiconductor chip11and the substrate530at a low temperature by the thermosetting resin, and the thermal stress during manufacturing the semiconductor device510can be reduced.

Roughening by the metal fiber of the interconnection members516bis realized, and the adhesion with the sealing resin is improved. Since the other ends516t2of the interconnection members516bcan be mounted on the substrate by the low temperature heat treatment, the thermal stress during the substrate mounting can be reduced, resin peeling or the like can be prevented and the environmental resistance can be improved.

According to the embodiments described above, a semiconductor device including a package having improved heat dissipation performance and a method for manufacturing the semiconductor device can be realized.