JPH10242220A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the bonding failure between Au bumps and Cu leads and improve the productivity and reliability by forming Sn plating layers on the bumps and leads and thermocompression-bonding to form Au-Sn eutectics between or near the bumps and leads. SOLUTION: Au bumps 2 deposited on a semiconductor substrate 1 has an Sn plating layer 3 formed thereon before bonding the bumps 2 to Cu leads 4. An Sn plating layer 5 is formed on the surface of the leads 4 and thermocompression-bonded to the bumps to form Au-Sn eutectics 6 at and near their contacts. The plating of Sn, a low m.p. metal, on their surfaces facilitates welding and flowing of Au-Sn to improve the wettability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device,
In particular, the present invention relates to a semiconductor device for joining a lead to a gold (Au) bump electrode.

[0002]

2. Description of the Related Art Conventionally, automation of a process of bonding a lead to an electrode of a semiconductor device has been advanced, and an end portion of the lead attached to an appropriate carrier tape and an Au formed on a semiconductor substrate have been developed.
A method of bonding with a bump electrode, a so-called tape carrier (TCP) method, has been widely adopted.

FIG. 3 is a cross-sectional view of a semiconductor device for explaining an example of the related art. As shown in FIG. 3, a conventional semiconductor device includes an Au bump 2 attached on a semiconductor substrate 1 and a Cu (Cu) material in which a tin (Sn) plating layer 5 is formed on a surface of a copper (Cu) material.
The Cu bump 4 is joined to the Au bump 2.

In order to join the Au bump 2 and the Cu lead 4, the Sn-plated Cu lead 4 must be
A method of welding to the bumps 2 is mainly used. In such a combination of metals, a contact portion (that is, a contact) Au is formed by the Sn plating layer 5 of the lead portion 4 and the Au bump 2.
-An Sn alloy is formed and joined.

[0005] However, the melting of such a metal and Au-Sn is poor, which is a major cause of the non-adhesion of the lead portion 4.

Further, the Au bumps 2, the Sn plating lead portions 4, and the Au—Sn alloy have poor wettability, which is also a factor of non-adhesion of the two.

[0007]

The above-described conventional semiconductor device has a disadvantage that lead non-adhesion occurs due to insufficient melting of Au-Sn at the time of thermocompression bonding of a lead portion and a bump.

In the conventional semiconductor device, the lead is Sn
In contrast to the plating, the bumps are not Sn-plated, so that the Au—Sn alloy is insufficiently wetted, resulting in a high non-adhesion rate of the lead itself.

An object of the present invention is to provide a semiconductor device capable of reducing the non-adhesion between the bump and the lead portion and improving the productivity and reliability.

[0010]

According to the present invention, there is provided a semiconductor device comprising:
When having an Au bump having an Sn plating layer formed on the upper surface and a lead portion having an Sn plating layer formed on the surface while being attached on the semiconductor substrate, and bonding the lead portion to the Au bump by thermocompression bonding , And an Au-Sn eutectic is formed at the contact portion between them and the vicinity thereof.

In the semiconductor device of the present invention, the A
The u bump is configured to form a Sn plating layer over the entire exposed surface.

[0012]

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1A and 1B are cross-sectional views of a semiconductor device before and after joining a lead and a bump, respectively, for explaining an embodiment of the present invention. First, as shown in FIG. 1A, the semiconductor device of the present embodiment has an Au bump 2 and a Cu lead portion 4 and is attached on the semiconductor substrate 1 before joining the two. The Au bump 2 forms the Sn plating layer 3 on the upper surface, while the Cu lead portion 4 forms the Sn plating layer 5 on the surface. Here, the Sn plating layer 3 is formed only on the upper surface of the Au bump 2, but the side surface of the bump 2 may be covered with an insulating film or the like and plated.

Next, as shown in FIG. 1 (b), when the Cu lead portion 4 is bonded to the Au bump 2 by thermocompression bonding, an Au-Sn eutectic 6 is formed at the contact portion between the two. This A
The u-Sn eutectic 6 is formed not only at the contact portion between the two but also around the vicinity thereof. At this time, the Sn of the Cu lead 4
In the plating layer 5, a portion that does not become the Au-Sn eutectic 6, that is, an upper portion is temporarily melted by heat at the time of thermocompression bonding, and then cooled and fixed.

As described above, when the Cu lead portion 4 and the Au bump 2 are fused by the Au-Sn eutectic 6, the respective surfaces are plated with Sn, which is a low-melting metal, so that the fusion is facilitated. , Au—Sn can be improved, and the wettability can be improved.

FIG. 2 is a sectional view on the bump side of a semiconductor device for explaining another embodiment of the present invention. As shown in FIG. 2, in the present embodiment, the Au plating 2 in the semiconductor device has the Sn plating layer 3 formed on the entire exposed surface including the side surface as well as the upper surface. In this case, Sn plating may be applied without covering the side surface of the bump 2 with the insulating film.

As a result, the Au bumps 2 are also formed on the side surfaces of the Au bumps 2.
-Sn eutectic flows more easily, and the peel strength of the lead portion further increases.

[0018]

As described above, in the semiconductor device of the present invention, the Au-Sn flow is improved by forming the Sn plating layers on the surfaces of the Au bumps and the Cu lead portions, respectively. It is possible to improve the solder wettability when the Cu lead portion is thermocompression-bonded, and it is possible to reduce non-adhesion between the two.

Further, the semiconductor device according to the present invention is preferably composed of Au-Sn
This reduces the number of connection failures due to the shortage of flow, thereby improving productivity and reliability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a semiconductor device according to an embodiment of the present invention before and after bonding a lead and a bump.

FIG. 2 is a sectional view on a bump side of a semiconductor device for explaining another embodiment of the present invention;

FIG. 3 is a cross-sectional view of a semiconductor device before bonding leads and bumps for explaining an example of the related art.

[Explanation of symbols]

 Reference Signs List 1 semiconductor substrate 2 Au bump 3 Sn plating layer 4 Cu lead portion 5 Sn plating layer 6 Au-Sn eutectic

Claims (2)

[Claims] An Au bump having an Sn plating layer formed on an upper surface thereof and a lead having an Sn plating layer formed on a surface thereof, wherein the Au bump has a lead portion formed thereon. A semiconductor device, wherein an Au-Sn eutectic is formed at a contact portion between the two and at the vicinity thereof when joining by crimping. 2. The semiconductor device according to claim 1, wherein the Au bump has an Sn plating layer formed on the entire exposed surface.