Crystallization Behaviour of Electroless Ni-P UBM with Medium Phosphorous Induced by Single and Step Heat Treatment

Abstract

This study examined the crystallization behavior of electroless Ni-P UBM with an medium phosphorous content (∼15 at%) induced by a single and step heat treatment using in-situ transmission electron microscopy (TEM). Different heat treatment processes affected the crystallization behavior of electroless Ni-P UBM. After single heat treatment at 300°C for 60 min, the electroless Ni-P UBM contained Ni and Ni₃P. In addition to Ni and Ni₃P, more complex Ni-P compounds, such as Ni₁₂P₅ and Ni₅P₂ formed in the electroless Ni-P UBM resulting from a step heat treatment at 150°C for 60 min followed by 300°C for 60 min.