Dielectric Properties of Thermal and Plasma-Assisted Atomic Layer Deposited Al[sub 2]O[sub 3] Thin Films

Abstract

A comparative electrical characterization study of aluminum oxide Al 2 O 3 deposited by thermal and plasma-assisted atomic layer depositions ALDs in a single reactor is presented. Capacitance and leakage current measurements show that the Al 2 O 3 deposited by the plasma-assisted ALD shows excellent dielectric properties, such as better interfaces with silicon, lower oxide trap charges, higher tunnel barrier with aluminum electrode, and better dielectric permittivity k = 8.8, than the thermal ALD Al 2 O 3 . Remarkably, the plasma-assisted ALD Al 2 O 3 films exhibit more negative fixed oxide charge density than the thermal ALD Al 2 O 3 layers. In addition, it is shown that plasma-assisted ALD Al 2 O 3 exhibits negligible trap-assisted Poole-Frenkel conduction unlike the thermal ALD Al 2 O 3 films, resulting in higher breakdown electric fields than the thermal ALD prepared films.