Interdependence of Parameters in Reactive Sputtering of Manganese in Oxygen

Abstract

Manganese oxide thin films deposited over the Ta205 layer in tantalum capacitors are known to improve yield and reliability. In this investigation reactive sputtering is used to prepare manganese oxides. The results show that films with resistivities below 1 ohm-cm can be produced, but the interdependence of oxygen partial pressure, power input, and substrate temperature limits the deposition rates that can be obtained without producing oxide phases with higher resistivities.With d-c sputtering at 4.0 kV, Mn203 is produced as the oxygen pressure increases from 3 X 10 -2 to 4 X 10 -2 Torr. This corresponds to a substrate temperature increase from 275 ~ to 360~ and a 50% increase in deposition rate. The complexity of the interactions in both d-c and rf reactive sputtering is further illustrated by the maximum in substrate temperature obtained with argonoxygen mixtures containing 0.5% O2. For reactive sputtering of materials similar to Mn-O, where several phases and variable stoichiometry are possible, it is therefore necessary to determine experimentally the conditions of power density, pressure, and substrate temperature that give the maximum deposition rate for each phase.

Atomistic growth phenomena of reactively sputtered RuO2 and MnO2 thin films

“…Locker et al 17 used DC reactive sputtering to synthesize MnO, Mn 3 O 4 , Mn 2 O 3 , and MnO 2 at substrate temperatures from 275 C to 360 C in pure O 2 or O 2 -Ar mixtures with a total working pressure up to 6.7 Pa. They discussed deposition rates and electrical resistivity of these thin films.…”

“…They discussed deposition rates and electrical resistivity of these thin films. 17 Recently, Tompsett et al 18 have explored the energetics of MnO 2 surfaces and vacancy formation thereon using density functional theory (DFT) at 0 K. They have identified that the (110) surface is the most stable and O vacancies were suggested to lead to MnO 2 decomposition. 18 This is valuable in terms of fundamental understanding, but the underlying atomic scale mechanisms defining the structure evolution during MnO 2 growth are still unknown.…”