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Ag-based alloy wire for semiconductor package

Ag-based alloy wire for semiconductor package description/claims

This application claims the benefit of Korean Patent Application No. 10-2007-0031998, filed on Mar. 30, 2007, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

1. Field of the Invention

The present invention relates to a semiconductor package, and more particularly to a silver (Ag)-based alloy wire for wire bonding.

2. Description of the Related Art

In semiconductor packages, semiconductor chips can be electrically connected to a package substrate using wire bonding. In conventional semiconductor packages, an aluminum pad of a semiconductor chip and a package substrate are bonded using gold (Au) wires. Au has been widely used because of its high chemical stability and high electrical conductivity. However, in order to meet the continuous demand to decrease the manufacturing costs in the semiconductor industry and address the cost increase of gold price, a new wire that replaces the Au wire is required.

For example, Japanese Patent Application Laid-open Nos. 1998-326803, 1999-67811, 1999-67812, and 2000-150562 disclose Au—Ag alloy wires. However, such Au—Ag alloy wires still include Au at high composite rates, which limits the cost reduction.

An Ag wire that is cheap by 30 to 50% of the conventional Au wire may be regarded as another example. However, the Ag wire has a reliability problem when bonded to the aluminum (Al) pad. Particularly as illustrated in FIG. 1, when performing a high humidity reliability test, a bonding surface of the Ag wire and the Al pad are most likely corroded or a chip crack occurs so that a bonding strength is significantly decreased. The high humidity reliability test is generally carried out using a pressure cooker test (PCT). The bonding strength of the Au wire is scarcely changed even after 96 hours in the PCT, but that of the Ag wire reaches nearly zero even after 24 hours in the PCT.

Moreover, the Ag wire has a drawback of a poor plasticity, which degrades product yield. Therefore, fabrication of the Ag wires requires many heat annealing operations, which increases the manufacturing costs.

The present invention provides an Ag-based alloy wire for a semiconductor package, which is highly reliable and requires low fabricating costs.

According to an aspect of the present invention, there is provided an Ag-based alloy wire for a semiconductor package, comprising 0.05˜5 wt % of at least one kind of a first additive ingredient selected from the group consisting of platinum (Pt), palladium (Pd), rhodium (Rh), osmium (Os), gold (Au), and nickel (Ni), and Ag as a remainder.

According to another aspect of the present invention, there is provided an Ag-based alloy wire for a semiconductor package, comprising 3 wtppm˜5 wt % of at least one kind of a second additive ingredient selected from the group consisting of copper (Cu), beryllium (Be), calcium (Ca), magnesium (Mg), barium (Ba), lanthanum (La), cerium (Ce), and yttrium (Y), and Ag as a remainder.

According to another aspect of the present invention, there is provided an Ag-based alloy wire for a semiconductor package, comprising 0.05˜5 wt % of the first additive ingredient, 3 wtppm˜5 wt % of the second additive ingredient, and Ag as a remainder.

The term wt % or wtppm refers to a ratio of weight of ingredients to total weight of a wire in terms of % or ppm.

The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:

FIG. 1 is a graph illustrating the high humidity reliability between an Au wire and an Ag wire in a pressure cooker test (PCT).

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• Utility Patent

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