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

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.