1. Field of the Invention
The present application relates to a semiconductor structure and a manufacturing method thereof. More particularly, the present application relates to a chip package structure and a manufacturing method thereof.
2. Description of Related Art
A wire bonding technology applied for electrically connecting a chip to a carrier is a common chip package technology. Here, the carrier is a circuit substrate, for example. In general, the wire bonding technology is applied by forming a wire bump on a pad of the carrier with use of a stud bump machine, extending a wire upward to a certain distance, pulling the wire down to a contact pad of the chip, and then stitching the wire. By applying the wire bonding technology, the chip and the carrier can be electrically connected to each other through the bonding wire, and signals can be transmitted between the chip and the carrier through the bonding wire as well.
At present, a material of the common bonding wire includes aluminum, copper, or gold, and technologies of fabricating the aluminum bonding wire have developed vigorously and attained to maturity. Nonetheless, in consideration of certain characteristics of aluminum, such as high resistance and electromigration, copper with an electromigration resistivity 30 to 100 times higher than that of aluminum replaces aluminum to serve as the material of the bonding wire. To be more specific, thermal conductivities of copper, gold, and aluminum are approximately 394 W/m° K., 293 W/m° K., and 247 W/m° K., respectively. Therefore, it can be deduced that copper is characterized with better thermal conductivity than that of aluminum and that of gold. However, copper is prone to be oxidized, and utilization of copper as the material of the bonding wire likely gives rise to oxidation, such that reliability and strength of the bonding wire both decrease. On the other hand, given that gold having a lower thermal conductivity than that of copper is employed as the material of the bonding wire, the bonding wire is not subject to oxidation, whereas manufacturing costs of the bonding wire are raised due to high costs of gold in comparison with costs of copper and aluminum. As such, it is rather imperative to reduce the manufacturing costs of the bonding wire and simultaneously maintain reliability and strength of the bonding wire.