JP3963914B2 - Semiconductor device - Google Patents

Description

The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly to a semiconductor device in which a plurality of semiconductor chips are mounted in a plane or in an overlapping manner and a method for manufacturing the same.

In recent years, a plurality of chips are packaged in one package in order to increase the capacity of the memory and to expand the circuit function.

For example, FIG. 7 shows a semiconductor device 3 in which two semiconductor chips 1 and 2 are two-dimensionally arranged and packaged in one package. The semiconductor device 3 includes a lead frame, and a large number of leads 6 are arranged around the first die pad 4 and the second die pad 5. A bridge 7 is disposed between the first die pad 4 and the second die pad 5. The first semiconductor chip 1 is fixed on the first die pad 4, the second semiconductor chip 2 is fixed on the second die pad 5, and the first bonding pads of the semiconductor chips 1 and 2 are fixed. A thin metal wire 10 is connected between 8 and the second bonding pad 9 on the lead 6. Further, a bridge 7 is used to electrically connect the first semiconductor chip 1 and the second semiconductor chip 2. That is, the bonding pad 8 and the bridge 7 of the first semiconductor chip 1, and the bridge 7 and the bonding pad 8 a of the second semiconductor chip 2 are connected via the thin metal wire 10. The whole is packaged in one package with the insulating resin 11.

The fine metal wires 10 are connected by ball bonding on one side and stitch bonding on the other side. In this stitch bonding, since ultrasonic waves are applied for a long time to cause deterioration of the semiconductor chip, ball bonding is adopted on the semiconductor chip side, and stitch bonding is adopted on the bonding pad side on the lead 6.

However, when the first semiconductor chip 1 and the second semiconductor chip 2 are directly connected by the thin metal wires 10, one of the semiconductor chips is always connected by stitch bonding. Therefore, in this structure, by forming the bridge 7, both semiconductor chips are configured to be connected by ball bonding.
JP-A-11-40741

However, in the lead frame of FIG. 7 described above, the leads 6 are connected by tie bars and are easy to handle. However, since the bridge 7 is formed in an island shape, it falls as it is. Various ideas have been applied.

Here, a connecting piece 12 for connecting the first die pad 4 and the second die pad 5 is provided, and the connecting piece 12 and the bridge are bonded together with an adhesive tape 13.

However, since heat is applied at the time of molding, the adhesive tape 13 needs heat resistance, is expensive, and has a problem of increasing the cost as a semiconductor device.

Further, as a method of supporting the bridge 7 without dropping, a method of forming a lead pattern including a bridge on a support substrate such as a flexible sheet, a ceramic substrate, or a printed substrate and molding the lead pattern is conceivable. However, if this support substrate is adopted, there is a problem that the semiconductor device becomes thick and the cost increases. Further, since the semiconductor chip molded on the support substrate is thermally insulated by the support substrate, there is a problem that the temperature of the semiconductor chip rises. In particular, when the temperature of the semiconductor chip rises, there is a problem that the drive current and the drive frequency are lowered, and the original capability of the semiconductor chip cannot be brought out.

  The present invention includes a first semiconductor chip and a second semiconductor chip arranged face down, a bridge that electrically connects the first semiconductor chip and the second semiconductor chip, and the first semiconductor. An external connection electrode provided below the chip and the electrode of the second semiconductor chip, at least a part of the back surface of which is a connection electrode to the outside, the first semiconductor chip, the second semiconductor chip, and the bridge And an insulating resin for sealing the external connection electrode, and the back surface of the bridge and the external connection electrode is exposed from the insulating resin.

The present invention has a structure capable of half-etching a conductive pattern through a conductive film or a photoresist. Furthermore, the plate-like body can be configured as an external connection electrode of a semiconductor device or a conductive pattern of a bridge without being pulled out from the front to the back by pressing or etching, and stopped in the middle. With this structure that can employ half-etching, the interval between the conductive patterns can be narrowed, and a finer pattern becomes possible. In addition, since the die pad, the external connection electrode, and the bridge are integrally formed with the plate-like body, deformation and warpage can be suppressed, and tie bars and suspension leads can be eliminated. Furthermore, after the insulating resin is sealed and completely fixed, the conductive pattern can be separated by polishing or etching the back surface of the plate-like body, and the conductive pattern is arranged at a predetermined position without any displacement. be able to. In particular, the bridge is conventionally supported by using an adhesive tape, but according to the present invention, the bridge can be embedded in an insulating resin without using this support means.

Further, since the insulating resin is formed on the half-etched sheet-like conductive foil, burrs generated between the leads can be eliminated.

Further, when the plate-like body is made of Cu as the main material and the conductive film is made of Ni, Ag, Au, Pd, or the like, the conductive film can be used as an etching mask. Can be formed into a curved structure, or an eave by a conductive film can be formed on the surface of the conductive pattern, thereby providing a structure having an anchor effect. Accordingly, it is possible to prevent the conductive pattern located on the back surface of the insulating resin from coming off and warping.

In addition, a semiconductor device manufactured using a plate-like body is composed of a semiconductor element, a conductive path such as a conductive pattern, and a minimum necessary amount of an insulating resin, and becomes a semiconductor device with no waste of resources. Therefore, a semiconductor device that can greatly reduce the cost can be realized. Further, by optimizing the coating thickness of the insulating resin and the thickness of the conductive foil, it is possible to realize a semiconductor device that is very small, thin, and lightweight.

In addition, when the semiconductor element is directly fixed to the die pad via a conductive film such as brazing material, Au, Ag, etc., the back surface of the die pad is exposed, so that the heat generated from the semiconductor element is directly transferred to the mounting board via the die pad. Can tell. In particular, this heat dissipation enables the mounting of power elements.

In addition, this semiconductor device has a structure in which the back surface of the separation groove and the back surface of the conductive pattern have a flat surface that is substantially the same. Even when a narrow pitch QFP or the like is mounted on a mounting substrate, Since it can be moved horizontally as it is, it is very easy to correct the displacement of the external extraction electrode.

Further, the whole is supported by the plate-like body until the insulating resin is applied, and the insulating resin serves as a support substrate for separation and dicing of the conductive pattern. Therefore, as described in the conventional example, there is no need for a support substrate, and there is an advantage that the cost can be reduced.

(Configuration of semiconductor device)
1A is a plan view of a semiconductor device according to the present invention, and FIGS. 1B to 1E are cross-sectional views corresponding to the line AA of FIG. 1A. 1B to 1E show the back surface structure of the semiconductor device.

The present invention is characterized in that by adopting the semiconductor chips 54 and 55 for face-down, the external connection electrode 52 can be disposed directly under the semiconductor chip, and the planar area and thickness of the semiconductor device can be reduced.

The first semiconductor chip 54 and the second semiconductor chip 55 can utilize face-down bare chips, flip chips, SMDs, wafer scale CSPs, and the like, and are externally connected to positions corresponding to the electrodes on the semiconductor chips 54 and 55. An electrode 52 is provided. Then, the external connection electrode 52 and the electrodes on the semiconductor chips 54 and 55 are connected through connection means. As this connection means, Au bump, brazing material, solder ball, conductive ball, anisotropic conductive resin, or the like can be used.

The bridge 53 is formed integrally with the external connection electrodes 52 a and 52 b, and extends from the bonding pad 59 of the first semiconductor chip 54 to the bonding pad 60 of the second semiconductor chip 55.

The heat of this semiconductor device is only transmitted through the solder balls and is inferior in heat dissipation. However, it is possible to prevent the temperature rise of the semiconductor chip by exposing the back surfaces of the semiconductor chips 54 and 55 from the insulating resin 61 and by reducing the thickness of the insulating resin on the back surfaces of the semiconductor chips 54 and 55. Moreover, you may attach a radiation fin to the back surface side of a semiconductor chip.
According to the present invention, the external connection electrode 52 and the bridge 53 are not supported by a connecting piece such as a support lead or a tab suspension lead, but are sealed with an insulating resin 61 independently. In addition, these independent external connection electrodes 52 and bridges 53 are sealed without adhesive tape. Therefore, the finished product does not have the cut portion of the connecting piece.
A conventional lead frame is completed by cutting off connecting members such as suspension leads and tie bars. That is, it is processed as a finished product from the front surface of the lead to the side surface and back surface. Therefore, since it is a finished lead frame, a connecting member is required. And after mounting a semiconductor chip on this lead frame, it sealed with insulating resin and cut | disconnected this connection member. Therefore, the bridge 7 arranged in an island shape without being connected anywhere is only bonded and fixed by a support member such as the adhesive tape 13 as shown in FIG.
However, in the present invention, on the lead frame manufacturing side, the conductive foil is half-etched, and the external connection electrode 52 and the bridge 53 are supplied to the semiconductor manufacturer in a semi-finished product state. Then, the semiconductor manufacturer performs device mounting, electrical connection, and sealing with an insulating resin, and finally the external connection electrode 52 and the bridge 53 so that the shape of the external connection electrode 52 and the bridge 53 is separated over the entire area. The back side is processed. Therefore, it is possible to obtain a finished product without using a connecting member such as a tab suspension lead or an adhesive tape, and without mechanical separation of the connecting member.

(Method for manufacturing semiconductor device)
A process until the semiconductor device 80 is manufactured using a conductive foil mainly made of Cu will be described with reference to FIGS.

First, a plate-like body 81 made of a conductive foil is prepared as shown in FIG. In the plate-like body 81, the first surface 82 and the second surface 83 are flat, and a conductive film 84 or a photoresist having a conductive pattern formed on the second surface 83 is formed. The conductive pattern is a hatched portion as shown in FIG. When a photoresist is employed instead of the conductive film, the conductive film is formed at least in a portion corresponding to the bonding pad in the lower layer of the photoresist.

Subsequently, the plate-like body 81 is half-etched through the conductive film 84 or the photoresist. The etching depth should be shallower than the thickness of the plate-like body 81. Note that the shallower the etching depth, the finer the pattern can be formed.

Then, by half-etching, the conductive pattern appears in a convex shape on the second surface 83 of the plate-like body 81. The plate-like body 81 may be a Cu—Al laminate or an Al—Cu—Al laminate. In particular, an Al—Cu—Al laminate can prevent warping caused by a difference in thermal expansion coefficient. (See Figure 3 above)
Subsequently, the semiconductor element 85 is fixed to the semiconductor element mounting region, and the bonding electrode of the semiconductor element 85 and the first pad 86 are electrically connected. In the drawing, since the semiconductor element 85 is mounted face-up, a thin metal wire 87 is employed as the connecting means.

In this bonding, since the first pad 86 is integral with the plate-like body 81 and the back surface of the plate-like body 81 is flat, it comes into contact with the table of the bonding machine. Therefore, if the plate-like body 81 is completely fixed to the bonding table, the bonding energy can be efficiently transmitted to the fine metal wire 87 and the first pad 86 without the positional displacement of the first pad 86. Therefore, it is possible to improve the connection strength of the fine metal wires for connection. The bonding table can be fixed, for example, by providing a plurality of vacuum suction holes on the entire surface of the table.

In addition, when adopting a face-down type semiconductor element, the electrodes on the semiconductor element 85 are formed with solder balls, bumps such as Au and solder, and the first pad 86 is arranged directly below the bumps. It is fixed. See FIG. 1 for details.

The passive element may be fixed to the pad 86 via a brazing material such as solder, a conductive paste such as Ag paste, or the like. Note that passive elements that can be employed here include a chip resistor, a chip capacitor, a printing resistor, and a coil. (See Figure 4 above)
An insulating resin 89 is formed so as to cover the conductive pattern, the semiconductor element 85, and the connecting means. The insulating resin may be either thermoplastic or thermosetting.

Further, it can be realized by transfer molding, injection molding, dipping or coating. As the resin material, a thermosetting resin such as an epoxy resin can be realized by transfer molding, and a thermoplastic resin such as a liquid crystal polymer and polyphenylene sulfide can be realized by injection molding.

In the present embodiment, the thickness of the insulating resin is adjusted so that about 100 μm is covered from the top of the thin metal wire 87. This thickness can be increased or decreased in consideration of the strength of the semiconductor device.

In the injection, since the conductive pattern is integrated with the sheet-like plate-like body 81, there is no displacement of the conductive pattern as long as the plate-like body 81 is not displaced.
Again, the lower mold and the back surface of the plate-like body 81 can be fixed by vacuum suction.

As described above, the insulating resin 89 is embedded with conductive patterns and semiconductor elements formed as convex portions, and the plate-like body 81 below the convex portions is exposed on the back surface. (See Figure 5 above)
Subsequently, the plate-like body 81 exposed on the back surface of the insulating resin 89 is removed, and the conductive patterns are individually separated.

Various methods can be considered for the separation step here, and the back surface may be removed by etching, or may be cut by polishing or grinding. Moreover, you may employ | adopt both. For example, if the insulating resin 89 is etched until it is exposed, there is a problem that the scraped scraps of the plate-like body 81 and the burr-like metal thinned outwardly bite into the insulating resin 89. Therefore, if the cutting is stopped just before the insulating resin 89 is exposed, and then the conductive pattern is separated by etching, the metal of the plate-like body 81 bites into the insulating resin located between the conductive patterns. It can be formed without. Thereby, the short circuit of the conductive patterns of a fine space | interval can be prevented.

When a plurality of units constituting the semiconductor device 80 are formed, there is a step of dicing the individual semiconductor devices 80 after this separation step.

Here, a dicing apparatus is employed to separate the components individually, but chocolate breaks, presses and cuts are also possible. (See Figure 6 above)
With the above manufacturing method, a light, thin and small package can be realized with three elements of a plurality of conductive patterns, a semiconductor element 85 and an insulating resin 89.

Next, effects produced by the above manufacturing method will be described.

First, since the conductive pattern is half-etched and supported integrally with the plate-like body, the substrate conventionally used as the support substrate can be eliminated.

Secondly, since the plate-like body is formed with a conductive pattern that is half-etched to form a convex portion, the conductive pattern can be miniaturized. Therefore, the conductive pattern width and the conductive pattern interval can be narrowed, and a package having a smaller planar size can be formed.

Thirdly, since it is composed of the above three elements, it can be configured with the minimum necessary amount, can eliminate wasteful materials as much as possible, and can realize a thin semiconductor device with greatly reduced cost.

Fourth, the die pad, the external connection electrode, the bridge, and the wiring are formed as convex portions by half-etching, and the individual separation is performed after sealing, so that tie bars and suspension leads are not necessary. Therefore, the formation of tie bars (suspending leads) and the cutting of tie bars (suspending leads) are completely unnecessary in the present invention. Furthermore, the bridge can be formed without the support of the adhesive tape.

Fifth, after the conductive pattern that became the convex portion is embedded in the insulating resin, the plate-like body is removed from the back surface of the insulating resin and the leads are separated. Resin burrs generated between the leads can be eliminated.

Sixth, since the back surface of the semiconductor element is exposed from the back surface of the insulating resin, heat generated from the semiconductor device can be efficiently released from the back surface of the semiconductor device.

It is a figure explaining the semiconductor device of the present invention. It is a figure explaining the manufacturing method of the semiconductor device of this invention. It is a figure explaining the manufacturing method of the semiconductor device of this invention. It is a figure explaining the manufacturing method of the semiconductor device of this invention. It is a figure explaining the manufacturing method of the semiconductor device of this invention. It is a figure explaining the manufacturing method of the semiconductor device of this invention. It is a figure explaining the semiconductor device using the conventional lead frame.

Explanation of symbols

50 First die pad 51 Second die pad 52 External connection electrode 53 Bridge 54 First semiconductor chip 55 Second semiconductor chip 56 Metal fine wire 57 Metal fine wire 58, 59, 60 Bonding pad 61 Insulating resin 62 Insulating film

Claims (4)

A first semiconductor chip and a second semiconductor chip arranged face down;
A bridge for electrically connecting the first semiconductor chip and the second semiconductor chip;
An external connection electrode provided below the electrodes of the first semiconductor chip and the second semiconductor chip, wherein at least a part of the back surface serves as a connection electrode to the outside;
An insulating resin that seals the first semiconductor chip, the second semiconductor chip, the bridge, and the external connection electrode;
The semiconductor device, wherein the bridge and the back surface of the external connection electrode are exposed from the insulating resin. An insulating coating is provided on the back surface of the insulating resin, the back surface of the bridge, and the back surface of the external connection electrode,
The semiconductor device according to claim 1, wherein at least a part of the external connection electrode is exposed from the insulating film.   2. The semiconductor device according to claim 1, wherein the back surfaces of the bridge and the external connection electrode are exposed to be recessed from the insulating resin.   2. The semiconductor device according to claim 1, wherein the bridge is disposed between the first semiconductor chip and the second semiconductor chip.

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