JPS5835953A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the discharge between a semiconductor base body and a metallic foil, and to improve reliability by making the surface of an electrode terminal, to which the metallic foil is connected, higher than the surface of the electrode of the base body. CONSTITUTION:The cathode electrode metallic foil 206 of one part of a composite electrode material 217 is soldered 212 to a supporting plate 210 and a gate electrode metallic foil 207 is soldered 213 to a supporting plate 211 respectively. The exposed surfaces of the metallic foil 206, 207 are made higher than the surface of an electrode 208 at that time. According to this constitution, since the flexible composite electrode material 217 made of a polyimide film, etc. is not adjoined to the exposed section of a p-n junction between the n type base 202 and p type base 203 of a GTOSCR substrate 200, discharge is not generated between the metallic foil and the SCR base body, and a composite electrode material particularly molded is unnecessitated and productivity is also improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, and more particularly to an improved semiconductor device in which flexible electrodes are attached to semiconductor pellets constituting the semiconductor device.

Semiconductor pellets. It is common for semiconductor pellets to have metal plates attached to one or both sides, and these metal plates are often approximately the same size as the metal electrodes on the semiconductor pellet. Figure 1 shows
An example of the structure of a conventional power semiconductor device is shown. (b) is (a
). A metal electrode film (not shown) is formed on both sides of the semiconductor pellet 105, and a metal plate having approximately the same shape as the metal electrode film is formed on both sides of the semiconductor pellet 105.Semiconductor pellet 105
The underside of the pellet mount is crimped or connected to plate 106 to conduct heat and electrical current. Semiconductor pellet 10
The upper surface of 5 has substantially the same shape as the electrodes of the two semiconductor regions, ribbon-shaped portions 102 and 103, and flat portion 1.
It is connected to a strip-shaped conductor having numbers 01 and 104. The flat portions 101 and 104 of the conductor are connected to an external lead-out member.

Conventionally, when the above-mentioned conductor was mechanically punched or cut, it was possible to form the above-mentioned ribbon-shaped part and flat part. However, this method increases the number of semiconductor device manufacturing steps such as molding and connection of conductors and the number of components.

A tape carrier method is known as a method for connecting a conductor connected to a semiconductor device to an electrode of a semiconductor pellet with high productivity. This is made by bonding a conductive metal foil to a continuous insulating film member and chemically etching the conductive metal foil into a desired shape. A portion of the conductive metal foil processed into a desired shape is connected to the metal electrode of the semiconductor pellet.

In order to continuously supply the tape, the members constituting the tape carrier include a thin insulating film member and a conductive metal foil, both of which have flexibility.

The problem that arises when using such a tape with conductive metal foil attached is that both the conductive metal foil and the insulating film member are flexible, so if the conductor wire is It is difficult to mold. Therefore, in a semiconductor device with a structure in which a conductive metal foil, a metal electrode of a semiconductor pellet, and a metal terminal for drawing out the conductive metal foil to the outside are integrated, the bond formed inside the semiconductor pellet is If the exposed portion on the outer periphery and the conductive metal foil are close to each other, a high electric field may be generated and discharge may occur, leading to loss of functionality as a semiconductor device.

An object of the present invention is to provide a semiconductor device with a novel structure that prevents discharge between a semiconductor pellet and a conductive metal foil.

Another object of the present invention is to provide a highly reliable semiconductor device.

A feature of the present invention is that the electrode terminal to which the metal foil is connected is used to electrically distance the metal foil connected to the electrode film formed on the main surface of the semiconductor substrate from the bonding end formed on the semiconductor substrate. The terminal surface of the semiconductor substrate is higher than the electrode surface of the semiconductor substrate.

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 2 shows the structure of an embodiment of the present invention using a GTO thyristor. Figure 2 (b) is the A-A' cross section of (a),
(C) is a BB' cross section of (a). In the figure, the thyristor base 200 includes a p emitter 201, an n base 202,
P base 203, N emitter 216, glass passivation 215. A canned metal electrode 209 is ohmically connected to the n emitter 216, a gate metal electrode 208 is a control electrode that is ohmically connected to the p base 203 exposed on the same surface as the exposed surface of the n emitter 216, and the p emitter 2
The anode electrode 204 is the other main electrode and is ohmically connected to the anode electrode 204. The gate metal electrode 208, the canned metal electrode 209, and the anode metal electrode 204 can be soldered. Good adhesion, (3) low resistivity, (4)
) A metal film is used that satisfies conditions such as ease of bonding with external wiring. In the present invention, cr-Ni-A
g The multilayer metal film is selectively removed by a lift-off method for the canned metal electrode 209 and the gate metal electrode 208.
The anode electrode 204 was formed on the entire surface.

In the figure, 217 is a carrier tape 205, a cathode electrode metal foil 206 made of conductive metal foil, and a gate electrode metal foil 2.
This is a composite electrode material made of 07.

The cathode metal foil 206 connects the cando metal electrode 209 of the GTO thyristor, and the gate electrode metal foil 207 connects the gate metal electrode 208 of the GTO thyristor to the solder layer 21.
4 and integrated. This composite electrode material 2
No. 17 is based on an organic insulating tape, and a conductive metal foil such as copper foil is bonded to the surface of the tape using an adhesive or by thermocompression bonding. carrier tape 20
5 can be used such as a polyester film which has excellent heat resistance, a polyester film which has poor heat resistance but is inexpensive, and a glass epoxy material which has poor transparency but excellent heat resistance.
Ru. As the adhesive, an epoxy adhesive or an imide adhesive can be used.

In this example, a polyimide film bonded to copper foil with an epoxy adhesive was used. The thickness of the copper foil and polyimide film is 1% each in terms of flexibility of the composite electrode material.
0 to 100 μW and 20 to 400 μm are desirable. In the example of the present invention, the copper foil was 35 μm thick, and the polyimide film was 125 μm thick. The shapes of the gate electrode metal foil 207 and the cathode electrode metal foil 206 are formed by etching the copper foil of the composite electrode material using a photoresist method and a resist printing method.

Canned electrode metal foil 20 that is part of composite electrode material 217
6 is a gate electrode metal foil 2 on a cando electrode support plate 210.
07 is a solder layer 206 on each gate electrode support plate 211.
It was connected with 207 and integrated. Cando electrode support plate 2
10. The gate electrode support plate 211 may be any member that can be joined by soldering, such as a copper plate, a steel plate, a clad plate, a member plated with nickel or the like on the surface of these materials, or a member plated with nickel or the like on the surface of a ceramic such as alumina. A plate plated or bonded with metal materials is used. As shown in the figure, a GTO thyristor substrate 200, a composite electrode material 21
7. Gate electrode support plate 211, cand electrode support plate 21
In the integrated structure of No. 0, the exposed surfaces of the cando/electrode metal foil 206 and the gate electrode metal foil 207 are made higher than the surface of the gate metal electrode 208 in the figure. With this structure, the flexible composite electrode material does not contact the GTO thyristor substrate 200 or come close to the exposed end of the pn junction between the n-base 202 and p-base 203 of the GTO thyristor substrate 200.

The above GTO thyristor base 200, composite electrode material 217,
The steps for manufacturing the integrated structure of the gate electrode support plate 211 and the cand electrode support plate 210 will be described below.

FIG. 3 shows a composite electrode tape 300 in which a large number of composite electrode materials 21-7 are continuously formed. In Figure 3, (b) is (a
) is shown. In this embodiment, the composite electrode tape 300 is a polyimide tape 301 with a thickness of 125 μm.
A copper foil (not shown) having a thickness of 35 μm was bonded to the substrate using an epoxy adhesive, sprocket holes 303 were punched out, and the copper foil was etched using a photo-etching method. At this time, the solder plated external drawer door 302 was left. The solder plated external drawer part 302 is used as an electrode.A.

The portion A' was masked by covering with tape, and solder layers 212, 213, and 214 were formed in a solder plating bath. Solder compositions include pb-8n system, pb-8n-Ag system, two-layer plating of pb and sn, and pb and pb-
The two-layer plating of 8N solder is excellent.

GTO? The connection between the iristor base 200 and the composite electrode material 217 is performed as follows. That is, first, the GTO Cyrisk substrate 200 is placed on a heated support substrate. Next, the gate metal electrode 208, the gate electrode metal foil 206 of the composite electrode tape 300 carried by the sprocket hole 303 above the canned metal electrode 209, the canned electrode metal foil 207'kGTO thyristor base electrode 208,
209 and is edge-connected to the solder layer 214.

The composite electrode tape 300 to which a plurality of G T' 0 thyristor substrates 200 were successively adhered was separated into individual GTO thyristor substrates 200 . The composite electrode material 217 integrated with the GTO thyristor base 200 is aligned with the gate electrode support plate 211 and the cando electrode support plate 210, and then connected through solder layers 212 and 213.

According to one embodiment of the present invention, the following effects can be obtained.

<1) Since the composite electrode material has flexibility, there is no need to use members molded into a special shape, and semiconductor devices can be manufactured with high productivity.

(2) Since the gate electrode metal foil and cando electrode metal foil of the composite electrode material are not close to the outer periphery of the GTO thyristor base, discharge occurs between the gate electrode metal foil and cando electrode metal foil and the GTO thyristor base. etc., and the reliability of the semiconductor device is improved.

FIG. 4 shows an example in which a semiconductor element according to an embodiment of the present invention is assembled into a package, and (b) is a cross section taken along line A-X in (a). A p e -Ni metal plate 401 and a copper heat sink/anode electrode plate 402 are used for mounting semiconductor devices.
are welded to form an integral structure, and a metal disk 403 made of MO, S, or W is joined to the anode electrode plate 402 via a solder layer 404. metal disc 403
A gate electrode metallized layer 405 and a cando electrode metallized layer 406 are formed on the upper surface, and the entire lower surface is covered with W'1.

A ceramic insulating substrate 407 metallized with bamboo MO or the like and an anode electrode of the GTO thyristor base 200 are connected via a solder layer 408, respectively. A gate electrode lead 409 and a canned electrode lead 410, which are silver-plated copper wires, are connected to a gate electrode metallized layer 405 and a canned electrode metallized layer 40, respectively, via a semicircular layer.
6.

FIG. 5 shows an example in which a semiconductor element according to an embodiment of the present invention is assembled into a package different from that in FIG. 4.

FIG. 5 Φ) shows the A-4 cross section of Ca). In the figure, a ceramic insulating substrate 502 made of alumina or the like metalized with W or MO is integrated with a copper heat sink plate 501 electrolytically plated with Ni on both sides via a solder layer 503tl-, and the upper surface of the insulating substrate 502 is metallized. A gate electrode plate 504, a canned electrode plate 505, and a metal disk 506 each using a copper plate coated on both sides with Ni plating are placed in the solder layers 507, 508, and 509, respectively.
connected via. A second metal disk 516 made of W or MO, which has a coefficient of thermal expansion close to that of the silicon substrate and relatively good thermal conductivity, is connected to the metal disk 506 via a solder layer 511 .

In the above embodiment, a GTO thyristor is used, but it goes without saying that the present invention can be applied to any semiconductor device such as a diode, a transistor, or a thyristor. Furthermore, the resin portion of the composite electrode tape may or may not remain after the semiconductor device is completed.

According to the present invention, (1) electrode leads can be electrically effectively taken out from the semiconductor substrate, and connection from the semiconductor substrate to external electrode terminals is easy, which facilitates the manufacture of semiconductor devices; can.

(2) A highly reliable semiconductor device with no electrical connection defects can be obtained.

(3) There is an effect that a semiconductor device without fear of short-circuit or discharge accidents can be easily obtained.

[Brief explanation of drawings]

Fig. 1 shows a conventional example of the present invention, and Figs. 2 to 1 show embodiments of the present invention. 200...Thyristor base, 205...Carrier tape, 217...Composite electrode material, 300...Composite electrode material Figure 3

Claims (1)

[Claims] 1. A semiconductor substrate having at least one main surface, a predetermined electrode film formed on the surface of the semiconductor substrate, a part connected to the electrode film and having substantially the same shape as the electrode film, and a part that is integral with this part and has the same shape as the electrode film. A semiconductor substrate to which the metal foil is connected, the metal foil comprising an external lead-out portion extending from the electrode film to the outside of the electrode film, and an electrode terminal connected to an end of the external lead-out portion of the metal foil. A semiconductor device characterized in that an electrode terminal surface to which the metal foil is connected is made higher than an electrode film surface.