JPS6032335A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the generation of purple plague and white plague and the generation of crack in the surface protective film and to enhance the reliability of the title device by a method wherein the upper metal of a protruded electrode is constituted of a part of lead wires connected by a wire-bonding method. CONSTITUTION:A semiconductor device is constituted of; a semiconductor substrate 11 made of Si, etc.; an insulating film 12 made of SiO2, etc., and formed on the semiconductor substrate 11; an Al pad 13 formed on the insulating film 12; a surface protective film 14 made of SiO2, Si3N4, etc., and formed on parts of the top surface of the Al pad 13 and the insulating coated film 12; a conductor 15 consisting of a metal for tight adhesion reinforcing formed on the top surface of the Al pad 13 made of Ti, Cr, etc., and a metal for barrier made of Pt, Cr, etc.; and a metal bump 16 consisting of a part of Au lead wires connected by a thermal press welding connestion method as a wire-bonding method. An external lead wire 17 to be connected to the metal bump 16 can be easily connected to the metal bump 16 either by leaving the form of the point of the external lead wire 17 as it has been previously bent according to the form of the recessed part or by using a lead material, which can be easily bent by pressure to apply at the bonding time, as the lead material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a semiconductor device, and particularly to a semiconductor device having a protruding electrode.

[Prior art]

Conventionally, in semiconductor devices such as integrated circuits, the most commonly used method for connecting device terminals and external leads is a wire bonding method.

When such a method is used, the semiconductor device used therein usually has the following structure. In other words, the surface of the semiconductor substrate has a diameter of 5.
It is covered with an insulating film such as i01, Si3N4, etc., and the connecting holes are connected by internal wiring metal to provide the necessary electrical connections.

The terminal end of such internal wiring, that is, the connection end with the external lead is usually called a pad, and is arranged at the periphery of the semiconductor substrate. A7 is usually used as the material for these internal wirings and pads from the viewpoints of conductivity, ohmic properties with silicon, workability, etc., and the surface of these internal wirings is nuclided with an insulator for the purpose of surface bonding. And then there's the thermocompression bonding method.

External leads are connected to the pads by ultrasonic crimping or the like.

On the other hand, in wireless bonding, which has recently been attracting attention, protruding electrodes made of metal protrusions (bumps) are prepared as external connection terminals, and connections with multiple metal external leads can be realized simultaneously. It is characterized by

Such a metal bump is usually formed on the pad portion of the normal structure for wire bonding.
, Cr-Cu-Au. Ti here.

Cr is applied to bumps and surface coating insulating film (Si02,5i3N
4) Au is a chemically stable metal that can easily form a protrusion structure by electroplating, and PL and Cu are bonded between Al, which is the wiring metal, and Au, which is the protrusion metal. It is used to avoid the appearance of malignant intermetallic compounds such as purple plague and white plague due to direct contact with.

FIG. 1 is a sectional view showing the structure of a protruding electrode of such a conventional wireless bonding semiconductor device.

A semiconductor substrate 1 made of silicon or the like is covered with an insulating film 2 of 5iOz or the like, an Al pad 3 is provided on this insulating film 2, and Si02 is deposited on the upper surface of this Al pad 3.

A conductor 5 made of a surface protection film 4 such as Si3N4, a metal for reinforcing adhesion such as Ti or Or, and a barrier metal such as Pt or Cu, and a metal bump 6 made of Au as an upper metal are formed. . Note that the metal bumps 6 are usually formed by electroplating.

When performing wireless bonding on a semiconductor device having such a structure, the external lead 7 to be connected to the metal bump 6 is brought into contact with the metal bump 6, and then exposed to high heat of approximately 450°C and 1 to 2.5 kg of heat. A high pressure of /cm2 is applied to the top surface of the contact for about 1 second to complete the bonding.

However, in the metal bump 6 of the conventional structure, as mentioned above, due to high pressure being applied during bonding, cracks occur in the pass isoelectric (+5) directly under the metal bump 6,
As a result, the bump metal (Au) and the pad wiring metal (Al) come into direct contact, resulting in the formation of purple plague with low mechanical strength and white plague with high electrical resistance. Metal Au forming bump 6 and surface protective film (Si02.5i3N4)
Due to the significant difference in thermal expansion coefficient between the metal pad 6 and the metal pad 6, cracks occur in the surface protection film 4 around the metal pad 6, impairing the bonding effect, which is a serious drawback in terms of reliability.

In order to compensate for the above drawbacks, it is possible to form the metal bumps 6 at a distance from the Al pads 3, but this requires a change in the design of the Al wiring pattern, which inevitably leads to an increase in the cost of the semiconductor device. Therefore, it is difficult to realize this goal.

[Purpose of the invention]

The object of the present invention is to eliminate the above-mentioned drawbacks, thereby eliminating the purple plaque generated during bonding.

It is an object of the present invention to provide a semiconductor device having a protruding electrode having a structure that is highly reliable and can be easily formed, preventing the occurrence of cracks in white plaque and a surface protective film.

[Explanation of Examples]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view showing essential parts of an embodiment of the present invention.

In this embodiment, a semiconductor substrate 11 made of silicon or the like, an insulating film 12 made of Si02 or the like formed thereon, and an insulating coating 1
5i02 formed on a part of the upper surface of the Al pad 13 and the insulating coating 12,
A surface protective film 14 made of 8i3N4 etc., Ti, Cr
A metal for reinforcing adhesion formed on the upper surface of the Al pad 13 made of PT.

A conductor 15 made of a barrier metal made of Cu or the like;
It is composed of a metal bump 16 made of a part of an Au1J-coated wire connected by a thermocompression bonding method as a wire bonding method.

That is, this embodiment differs from the conventional example shown in FIG. 1 in that the metal bumps are formed using a wire bonding method instead of the conventional electroplating method. The metal bumps 16 of this embodiment are Au1J connected by thermocompression bonding.
The wire bonding section is made by cutting off the wire except for the part on the four-wire conductor J5, and can be easily formed using current automated wire bonding equipment. Furthermore, bonding is carried out in a short time of about 3 seconds at a temperature of about 300°C and a pressure of about 5 kg/cm2, so that the conductor 15 and protective film 14 are Electrical 2
A mechanically stable gold peach bump can be obtained.

Furthermore, as shown in FIG. 2, the metal bump 16 thus formed has a recess formed in its upper part by pressure contact with the bonding electrode. Therefore, the shape of the tip of the external lead wire 17 to be connected to this metal bump 16 should be bent in advance to match the shape of this recess, or a lead material that can be easily bent by the pressure during bonding may be used as a lead material. By using this, connection can be made more easily than in the conventional example shown in FIG. Therefore, it becomes possible to perform pressure welding for a shorter time than in the past, and the occurrence of cracks during pressure welding, which conventionally occurs, is improved.

No. 3- is a sectional view showing a main part of another embodiment of the present invention.

In this embodiment, the metal bumps 16' are separated from the Al pads 13 by separating the lead wire portions of the metal bumps 16' made of Au leads formed by thermocompression bonding in the embodiment shown in FIG. It is constructed by cutting off the required length to reach the top of 14.

According to this embodiment, the lead wire 17' can be connected to the metal bump 16' at an appropriate location on the portion 14 shown in FIG. 3, and the reliability of the semiconductor device is not impaired during connection.

In the above description of the embodiments, although the thermocompression bonding method is used as the wire bonding method, it goes without saying that other wire bonding methods such as the ultrasonic bonding method may be used.

Also, although silicon is used as a semiconductor substrate,
It goes without saying that the present invention is also applicable to cases where other semiconductor substrates are used.

〔Effect of the invention〕

As explained above in detail, the semiconductor device of the present invention includes:
The protruding electrode has an upper metal (metal bump) made of a part of the lead wire connected by the wire punching method, so it is easy to form an electrically and mechanically stable protruding electrode, and it is also easy to connect external leads. This has the effect of providing a highly reliable semiconductor device that can prevent the occurrence of purple plaque and white plaque and cracks in the surface protective film, which sometimes occur conventionally.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the main parts of an example of a conventional semiconductor device;
FIG. 2 is a sectional view showing a main part of one embodiment of the present invention, and FIG. 3 is a sectional view showing a main part of another embodiment of the invention. 1... Semiconductor substrate, 2... Insulating coating,
3...Al pad, 4...Surface protection film, 5...Conductor, 6...-Metal bang, 7
...External lead, 11...Semiconductor substrate, 1
2...Insulating coating, 13...Al pad, 14...Surface preservation film, 15...Conductor, 16.16'... ...fiJ bump, 17.1
7'...External lead. 8/Figure/'1

Claims (1)

[Claims] 1. A semiconductor device having a protruding electrode, wherein an upper metal of the protruding electrode is formed from a portion of a lead wire connected by a wire bonding method.