Comparison of Metal Distribution and Bonding Characteristics according to FAB Formation Conditions

Several attempts have been made to lower the price of materials in the semiconductor market. Among them, the wire used for interconnection has a disadvantage of high material price in the field of using gold. Many packages have evolved to other technologies to improve performance and are moving away from wire bonding process, but many packages still use bonding wires. In the bonding wire market, in order to reduce prices, gold is being replaced by inexpensive copper, and now the market for copper wire coated with precious metals considering workability is dominant. [1], [5] However, due to the rigid nature of copper, packages with sensitive wiring structures are difficult to apply. [2] Silver alloy wire and noble metal coated silver wire have been developed to lower the wire price of these sensitive packages. [3] In the case of the recently developed noble metal coated silver wire, unlike a silver alloy bonding wire, a spherical ball shape can be realized without using inert gas when forming a Free Air Ball. Due to these advantages, it has recently been in the spotlight as a wire for replacing Au wire. [3] In this paper, experiments were conducted on the bonding conditions of silver wire coated with noble metals. The bondability of the prepared noble metal-coated silver wire according to the Free Air Ball formation conditions was verified. Specifically, evaluation was performed according to the current change at the time of Electronic Flame Off, the type of inert gas, and the size of the Free Air Ball. The evaluation confirmed the optimum bonding conditions for the application of the noble metal coated silver wire.