Low temperature plasma oxidation for advanced 3D CMOS-based devices



The required temperature in semiconductor process technology is going towards two extreme directions. Either very high temperatures (up to 1300 °C) with very short durations on the order of milliseconds are required for highest dopant activation, or extremely low temperatures are needed for forming high-quality dielectrics with minimum dopant deactivation and redistribution. This contribution describes a new microwave plasma oxidation apparatus with unique features addressing the before-mentioned low-temperature process requirements. With this new technique the oxide growth rate was studied as a function of time, gas ambient, pressure, applied microwave power and silicon substrate parameters to determine crystallographic oxidation rate anisotropy and dopant concentration independent oxidation at temperatures well below 500 °C. The “More Moore” approach of geometrical scaling in 2D will soon come to a physical end and therefore new requirements related to the thermal budget occur. Additionally the transition from 2D to 3D devices requires extremely conformal oxide growth. Both the low temperature and conformal oxide growth will be demonstrated on test structures. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)