Material Property Analysis of Amorphous Metallic Thin Films as Diffusion Barrier Layer

摘要

Copper has been widely used as an interconnect material due to its lower electrical resistivity and better thermomigration and electromigration resistance However as temperature and time increase during reflow process Cu-Sn intermetallic compound gradually produced excessive intermetallic compounds can result in poor reliability of solder bump In the current Ni as an barrier layer has been widely studied and industrially accepted in order to inhibit rapid copper diffusion in interconnect structures The proportion of intermetallic compound ratio in the solder bumps will be increased due to the shrinking of package devices In addition the current density in the solder bump needs to be increased under such high current density the thermomigrtion and electromigration in the solder bump becomes a serious reliability issue Amorphous metallic films have been considered to be the most effective barriers layer for Cu metallization due to the absence of grain boundaries and immiscibility with copper The time and cost required for nano-scale experimant may be exceedingly large and for this reason molecular dynamics have been used to analyze the material properties of CuAg and ZrCuNiAl amorphous metal films in this study including the glass transition process of amorphous metal films the effect of composition ratio and quenching rate on the internal microstructure of amorphous metal films diffusion Properties and the strength of the interface between polycrystalline and amorphous thin film The results show for CuAg alloys Cu20Ag80 present 50% amorphous at quenching rate of 25 K/ps but Cu40Ag60 and Cu60Ag40 present more than 95% of the amorphous at quenching rate Between 0 25 K/ps and 25 K/ps which indicates that it has a good glass forming ability For the diffusion side the better barrier performance with heigher of the amorphous ratio For the interfacial tensile test the ZrCuNiAl alloys which consist of four elements mixed together almost no strain occurs during tensile and the initial void will be generated at polycrystal Cu which indicates the strength of ZrCuNiAl/Cu interface is greater than polycrystal Cu From the experiment the sample with the Zr53Cu30Ni9Al8 TFMG barrier layer almost no IMC can be observed even after aging at 125°C for 500 hr which indicates that it has a good barrier effect

獎項日期	2018 7月 10
原文	English
監督員	Tei-Chen Chen (Supervisor)