Characteristics of high-order silane based Si and SiGe epitaxial growth under 600 ℃

Abstract

Low temperature Si and SiGe epitaxy have been crucial in the semiconductor industry, prompting interest in high-order silanes as Si precursors. In this study, we investigated the growth characteristics of Si and SiGe epitaxial layers using Si2H6, Si3H8, and Si4H10 precursors by ultra-high vacuum chemical vapor deposition at temperatures between 500℃ and 600 ℃. We examined the effects of each precursor on the growth behaviors through varying temperature and flow rate conditions. For these three precursors, activation energies for Si epitaxy were measured to be below surface H desorption energy, and an increase in the order led to a greater adatom density at equivalent flow rates. In SiGe epitaxy, we observed Ge composition variations with temperature at each Ge-to-Si flow ratio depending on the Si precursors. Si2H6 exhibited almost consistent Ge compositions across temperatures, and the activation energy for SiGe epitaxy was decreased to 1.73 eV when the flow ratio was increased to 1. In comparison, Si3H8 and Si4H10 exhibited negligible changes in Ge compositions for the flow ratios below 0.5, with activation energies of 1.88 and 1.62 eV, respectively. Based on our experimental results, we proposed potential reaction pathways for high-order silane precursors.