Optimization of Plasma Enhanced Atomic Layer Deposition Processes for Oxides, Nitrides and Metals in the Oxford Instruments FlexAL Reactor

Abstract

Hafnium oxide films deposited on silicon wafers from TEMAH and O 2 plasma showed saturation at growth rate per cycle of 1.1Å, which was independent of the plasma conditions. The same film deposited thermally using H 2 O as the oxidant saturated at 0.8Å/cycle. By varying the plasma exposure time the compositional ratio of [O]/[Hf], as calculated from RBS measurements, changed from 2.0 to 2.13. The carbon content in plasma HfO 2 films was < 2% compared to 8% in thermal HfO 2 films.Titanium nitride films deposited on silicon wafers from TiCl 4 and N 2 / H 2 plasma showed saturation at 0.33Å/cycle, which was independent of plasma conditions and a resistivity of <170µΩ cm at 350°C deposition temperature. The stoichiometry of the films can be changed from being slightly nitrogen rich to titanium rich by varying the N:H ratios in the plasma and limiting the amount of nitrogen available for the reaction. The chlorine impurity in TiN varied according to plasma exposure time (2.6% to 1.2%) and N 2 :H 2 gas ratio in the plasma, with a corresponding change in resistivity (200µΩ -150µΩ).

Tuning the Performance of Pt/HfO2/Ti/Pt ReRAM Devices Obtained from Plasma-Enhanced Atomic Layer Deposition for HfO2 Thin Films

“…The O/Hf-ratio was determined about (2.0 ± 0.1). This is consistent with data reported in the literature (5). Additionally, a stoichiometric the O/Hf ratio (≥ 2.0) fits well to the monoclinic phase of the material (1).…”

“…In comparison to thermal ALD, plasma-enhanced ALD (PE-ALD), where an O 2 -plasma is used as the oxygen source, is known for enabling the deposition of oxide thin layers with improved quality, full oxygen saturation (5) and low impurity content (6,7) even at low deposition temperatures. Resistive switching is based on the movement of oxygen vacancies and is therefore strongly influenced by the oxygen concentration in the materials, it is mandatory to control the oxygen amount at high reproducibility.…”