Reactively sputtered WSiN film suppresses As and Ga outdiffusion

Abstract

This paper evaluates reactively sputtered WSiN films as an annealing cap for GaAs substrate. WSiN film successfully suppresses As and Ga outdiffusion. The WSiN/SiO2 /SiN/substrate multilayer annealing cap reconfirms this. As and Ga accumulate in the WSiN/SiO2 interface after annealing at 800 °C for 20 min. The accumulated As peak concentration is estimated to be 1019 atoms/cm3 . X-ray diffraction shows WSiN film remains in an amorphous phase, exhibiting no recrystallized grain boundary. Film stress only changes by one-half before and after annealing. These characteristics are very different from other refractory metals such as WN and WSi which change from amorphous to crystalline phase after annealing. It is therefore concluded that reactively sputtered WSiN films prevent As and Ga outdiffusion and form a good annealing cap for GaAs.