JPH08213420A - Semiconductor device - Google Patents

Abstract

(57) [Summary] [Purpose] To achieve both low resistance and cost reduction. The bipolar transistor 1 includes a pad 16a of an emitter electrode 16 and a pad 15a of a base electrode 15 and respective inner leads 4b, 4 of a semiconductor pellet 2.
Gold wires 5A, 5B are bridged to both ends b by bonding both ends. A gold wire 5A on the emitter electrode 16 side,
The gold wire 5B on the base electrode 15 side has a different wire diameter, and the gold wire 5A on the emitter electrode 16 side is thick and the gold wire 5B on the base electrode 15 side is thin. [Effect] The gold wire 5 on the side of the emitter electrode 16 through which a large current flows
Since A is formed thick, it is possible to reduce the resistance, and since the gold wire 5B on the base electrode 15 side is formed thin, an increase in cost can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a semiconductor device in which each electrode of a semiconductor pellet and each lead are electrically connected by a wire using a gold wire. The present invention relates to a technique effectively used for an output bipolar transistor.

[0002]

2. Description of the Related Art Generally, a bipolar transistor consumes a large amount of power but operates at a high speed, so that it is used as a low frequency medium output transistor as a discrete device. In this type of bipolar transistor, gold wires are used to electrically connect the base electrode and emitter electrode of the semiconductor pellet to each lead in order to take advantage of high-speed performance while coping with large power consumption. .

In the conventional bipolar transistor, the wires used for the base electrode, the emitter electrode and the collector electrode are gold wires having the same diameter.

As an example of describing such an example, "Reliability Technology for Semiconductor Devices, Nikka Giren 1989.
Issued on February 3, 2013, edited by Tsuneo Azumi, "P1
The cross-sectional view of FIG. 5.11 at 30 shows the use of gold wire of the same diameter.

[0005]

In order to reduce the resistance of the bipolar transistor, it is desired that the wire have a thicker gold wire diameter. However, since the gold wire is expensive, simply increasing the wire diameter of the wire connected to the base electrode, the emitter electrode, and the collector electrode increases the manufacturing cost of the bipolar transistor.

An object of the present invention is to provide a semiconductor device which can achieve both low resistance and cost reduction.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0008]

The typical ones of the inventions disclosed in the present application will be outlined below.

That is, in a semiconductor device in which each electrode of a semiconductor pellet and each lead are electrically connected by a wire using a gold wire, the wire connected to the electrode through which a small current flows is formed thin. The wire formed on the electrode through which the large current flows is thick.

[0010]

According to the above-mentioned means, for example, a bipolar
In a transistor, the gold wire diameter of the wire connected to the emitter electrode is relatively thicker than the gold wire diameter of the wire connected to the base electrode, and the gold wire diameter of the base electrode side wire is the gold wire diameter of the emitter electrode side wire. It is made relatively thin compared to the diameter.

Therefore, if the gold wire diameter of the emitter electrode side wire is formed thicker than the conventional one and the gold wire diameter of the base electrode side wire is made thinner than the conventional one, the gold wire of the emitter electrode side wire through which a large current flows is formed. Since the diameter is large, low resistance can be realized, and since the gold wire diameter of the base electrode side wire is small, an increase in cost can be suppressed.

Further, by reducing the gold wire diameter of the base electrode side wire while keeping the gold wire diameter of the emitter electrode side wire as in the conventional case, the manufacturing cost can be reduced while keeping the electrical resistance substantially the same. be able to.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic circuit diagram of a bipolar
FIG. 3 shows a transistor, (a) is a front vertical sectional view, and (b) is a side vertical sectional view. 2 is a partially omitted plan view showing the lead frame, FIG. 3 is a partially omitted plan view of the lead frame after the wire bonding process, and FIG.
An enlarged cross-sectional view taken along line -a, and (b) is an enlarged vertical cross-sectional view of a pellet portion.

In this embodiment, the semiconductor device according to the present invention is constructed as a bipolar transistor. This bipolar transistor (hereinafter referred to as transistor) 1 includes a semiconductor pellet 2 in which a bipolar transistor circuit element is formed, a tab 3 to which the semiconductor pellet 2 is bonded, three leads 4, and a semiconductor. Two wires 5A and 5B bridging between the pellet 2 and the lead 4, a semiconductor pellet 2, a tab 3, a part of each lead 4 and each wire 5A, 5B are resin-sealed. The body 6 and the two wires 5A and 5B are formed by using gold wires having different wire diameters.

The semiconductor pellet 2 shown in FIG.
The semiconductor device is manufactured by forming bipolar transistor circuit elements in a wafer state in a so-called pre-process in the manufacturing process of a semiconductor device, and then dividing (dicing) into a small square thin plate shape. The semiconductor pellet 2 has a substrate 10, and a base 11 and an emitter 12 are provided on the substrate 10.
Are formed, and the collector 13 is formed in the lower part.

A silicon oxide film 14 is formed on the substrate 10 so as to cover the base 11 and the emitter 12. A base contact hole is formed at a predetermined position of the silicon oxide film 14 facing the base 11 so as to penetrate the base 11.
A base electrode 15 is formed in the contact hole. Similarly, the emitter 1 in the silicon oxide film 14
An emitter contact hole is formed so as to penetrate the emitter 12 at a predetermined position opposite to 2, and an emitter electrode 16 is formed in the contact hole. Further, a protective film 17 made of an insulating material is deposited on the silicon oxide film 14 so as to cover the surfaces of the base electrode 15 and the emitter electrode 16, and the base electrode 15 and the emitter of the protective film 17 are covered. Electrode 16
Holes for pads are respectively formed at positions opposed to, and the pads 15a and 16a are formed on the base electrode 15 and the emitter electrode 16 by the holes.

The base electrode 15 and the emitter electrode 1
Reference numeral 6 is formed by depositing an aluminum material (aluminum or its alloy) on the silicon oxide film 14 by an appropriate means such as sputtering deposition and then patterning it by photolithography. In addition, each pad is formed by depositing an insulating material such as PIQ by an appropriate means such as a coating method to form the protective film 17, and then patterning and opening by photolithography. On the other hand, on the lower surface of the substrate 10, a collector electrode 18 for the collector 13 is formed by depositing an aluminum material or the like.

One wire 5 of the two wires
A thick gold wire is used for A, and this wire (hereinafter referred to as a thick gold wire) 5A includes a pad 16a of the emitter electrode 16 formed on the semiconductor pellet 2 and an inner portion of one lead 4 (hereinafter, referred to as a thick gold wire). It is called Inner Reed.) It is bridged with 4b. A thin gold wire is used as the other wire 5B, and this wire (hereinafter referred to as a thin gold wire) 5B includes the pad 15a of the base electrode 15 formed on the semiconductor pellet 2 and the other inner lead 4b. Is bridged between. The collector electrode 18 formed on the semiconductor pellet 2 is electrically connected to the remaining inner lead 4b via the tab 3. In this way, the bipolar transistor circuit element built in the semiconductor pellet 2 in the resin sealing body 6 is electrically pulled out to the outside of the resin sealing body 6 by the lead 4.

In this embodiment, the thick gold wire 5A on the emitter electrode 16 side is formed relatively thicker than the thin gold wire 5B on the base electrode 15 side, and the thin gold wire 5A on the base electrode 15 side is formed. 5B is formed relatively thinner than the thick gold wire 5A on the emitter electrode 16 side. The wire diameter ratio between the thick gold wire 5A on the emitter electrode 16 side and the thin gold wire 5B on the base electrode 15 side is limited to 5: 2.

The transistor 1 is manufactured as follows. The lead frame is configured to be used in a transistor including a resin-sealed package, and is configured as the multiple lead frame 20. As the multiple lead frame 20, a thin plate made of a material having good conductivity such as a copper material (copper or copper alloy) is used.
As shown in FIG. 5, the unit lead frames 21 are integrally formed in a rectangular plate shape, and the unit lead frames 21 are arranged side by side so as to be repeated in the longitudinal direction. However, illustration and description will be made for one unit.

Each unit lead frame 21 is a pair of outer frames 2.
Outer portions (hereinafter referred to as outer leads) 4a of the three leads 4 are alternately connected to the outer frames 22 and 22. Each outer lead 4
Each inner lead 4b is linearly connected to a. Dam 2 between adjacent outer leads 4a, 4a
3 are each crosslinked. Further, the tab 3 is integrally formed at the tip of the inner lead 4b at the center. A plurality of positioning holes 24 are appropriately arranged and opened in the outer frame 22, and each unit lead frame 21, 2 is formed.
Section frame 25 that is bridged between both outer frames 22 between 1
It is divided by. Further, silver plating film portions 26 for enhancing bondability are formed on the surfaces of the tabs 3 and the two inner leads 4b, 4b at their tips.

The multiple lead frame 20 is used to bond the semiconductor pellets 2 onto the tabs 3 of the lead frame in the pellet bonding process. After that, in the wire bonding process, a suitable wire bonding device (not shown) such as an ultrasonic thermocompression bonding wire bonding device is used, and a thick metal is used between the semiconductor pellet 2 and the two inner leads 4b, 4b. The wire 5A and the thin gold wire 5B are bridged. That is, as shown in FIGS. 3 and 4, after one end of the thick gold wire 5A is first bonded to the pad 16a of the emitter electrode 16 of the semiconductor pellet 2, the middle part of the thick gold wire 5A is The second inner lead 4b facing the pad 16a is
Bonded and triggered. Similarly, after one end of the thin gold wire 5B is first bonded to the pad 15a of the base electrode 15, the middle portion of the thin gold wire 5B is second bonded to the inner lead 4b facing the pad 15a and triggered. To be

In this wire bonding step, since the thick gold wire 5A and the thin gold wire 5B respectively connected to the emitter electrode 16 and the base electrode 15 have different wire diameters, it is different from the wire bonding work on the emitter electrode 16 side. The wire bonding work on the side of the base electrode 15 is carried out at two stations. In this way, when the wire bonding work with the thick gold wire 5A and the wire bonding work with the thin gold wire 5B are performed at the two stations, both wire bonding operations are simultaneously performed in the multiple lead frame 20. As it does, there is no increase in time.

Next, although illustration and detailed description are omitted, the resin molding 6 is integrally molded into a substantially rectangular flat plate shape by a transfer molding device. The resin encapsulant 6 allows the semiconductor pellet 2, the thick gold wire 5A, and the thin gold wire 5B.
And each inner lead 4b is resin-sealed, and the three outer leads 4a are projected from the two side surfaces of the resin-sealed body 6.

Thereafter, in the cutting step, the resin sealing body 6
Unnecessary portions of the lead frame on the outside of the are cut off. Subsequently, the outer lead 4a is molded in the lead molding step to be molded into a desired gull wing shape.

According to the above embodiment, the following effects can be obtained. The gold wire on the base electrode side where a small current flows is thinner than before, and the gold wire on the emitter electrode side where a large current flows is formed thicker than before. Resistance can be realized.

When the thick gold wire on the emitter electrode side has the conventional wire diameter and the thin gold wire on the base electrode side has the smaller wire diameter than the conventional one, the electric resistance is substantially the same as the conventional one. The manufacturing cost can be reduced while maintaining the value.

When the gold wire on the base electrode side becomes thin, the area of the bonding pad of the base electrode to which the gold wire is bonded can be made small, so that the reduced amount can be used as an active area and the performance of the semiconductor pellet can be improved. You can

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, when gold wire connection is also applied to the collector electrode side, it is desirable to use a thick gold wire also on the collector electrode side.

In the above description, the case where the invention made by the present inventor is applied to a bipolar transistor which is the field of application which is the background of the invention has been described, but the present invention is not limited to this, and a MOS transistor or a semiconductor. It can be applied to all semiconductor devices such as integrated circuit devices (ICs).

When the present invention is applied to a MOS / transistor, the gold wire on the gate electrode side is formed relatively thinner than the gold wires on the source electrode side and the drain electrode side, and the gold wire on the source electrode side and the drain electrode side is formed. The gold wire may be formed relatively thicker than the gold wire on the gate electrode side.

When the present invention is applied to a weak current IC such as a memory IC or a logic IC, the gold wire on the small signal terminal side is formed relatively thinner than the gold wire on the driving terminal side. The gold wire on the driving terminal side may be formed relatively thicker than the gold wire on the small signal terminal side.

[0034]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

In a semiconductor device in which a wire using a gold wire is bridged between each electrode of a semiconductor pellet and each lead, the wire diameter of a wire through which a small current flows differs from that of a wire through which a large current flows. Since the wire on the small current side is formed thin and the wire on the large current side is formed thick, it is possible to realize the low resistance while suppressing the manufacturing cost.

[Brief description of drawings]

FIG. 1 shows a transistor which is an embodiment of the present invention,
(A) is a front vertical cross-sectional view, (b) is a side vertical cross-sectional view.

FIG. 2 is a partially omitted plan view showing a lead frame.

FIG. 3 is a partially omitted plan view of the lead frame after the wire bonding step.

FIG. 4A is an enlarged cross-sectional view taken along the line aa of FIG.
(B) is an enlarged vertical sectional view of a pellet portion.

[Explanation of symbols]

1 ... Bipolar transistor (semiconductor device), 2 ... Semiconductor pellet, 3 ... Tab, 4 ... Lead, 4a ... Outer lead, 4b ... Inner lead, 5A ... Thick gold wire (wire), 5B ... Thin gold wire (wire), 6 ... Resin sealing body, 1
0 ... Substrate, 11 ... Base, 12 ... Emitter,
13 ... Collector, 14 ... Silicon oxide film, 15 ... Base electrode, 15a ... Pad, 16 ... Emitter electrode, 16a ...
Pads, 17 ... Protective film, 18 ... Collector electrodes, 20 ... Multiple leadframes, 21 ... Unit leadframes, 22 ...
Outer frame, 23 ... Dam, 24 ... Positioning hole, 25 ... Section frame, 26 ... Silver plating film part.

Front page continued (72) Inventor Kenji Yoshida 15 Asahidai, Moroyama-cho, Iruma-gun, Saitama Pref. Inside Higashi Tobu Semiconductor Co., Ltd.

Claims (3)

[Claims] 1. In a semiconductor device in which each electrode of a semiconductor pellet and each lead are electrically connected by a wire using a gold wire, a wire connected to an electrode through which a small current flows is formed thin. A semiconductor device characterized in that a wire formed on an electrode through which a large current flows is formed thick. 2. The semiconductor device according to claim 1, wherein the electrode through which the small current flows is a base electrode or a gate electrode, and the electrode through which the large current flows is an emitter electrode or a source electrode. 3. The wire diameter ratio of the wire connected to the electrode through which the small current flows and the wire connected to the electrode through which the large current flows is 0.4 or more. Alternatively, the semiconductor device according to claim 2.