Oxygen Transport and Incorporation in Pt/HfO₂ Stacks Deposited on Germanium and Silicon

Abstract

Ge is a promising material to improve transistor performance. However, finding an efficient passivation strategy for this semiconductor is still a challenge. Annealing in O2 of metal/dielectric stacks prepared on Ge can improve the electrical properties of the final structure. However, excessive Ge oxidation cannot take place. O isotopic tracing in conjunction with subnanometric depth profiling of 18O were used to investigate oxygen transport and incorporation in Pt/HfO2/(Ge or Si) stacks. The supply of atomic oxygen (able to diffuse through HfO2) is a function of temperature and the number of available O2 dissociation sites in HfO2. A Pt top layer promotes a more efficient O2 dissociation, resulting in a higher O exchange in HfO2 and a higher O supply at the HfO2/semiconductor interface. The different nature of the native oxides of Si and Ge has a direct influence on the resulting physicochemical modifications of the stacks prepared on these semiconductor materials.