Effects of Low Temperature O2 Treatment on the Electrical Characteristics of Amorphous LaAlO3 Films by Atomic Layer Deposition

Abstract

Amorphous LaAlO3 films were deposited on hydrogen-terminated silicon substrates by atomic layer deposition (ALD) at 300 oC. The precursors were lanthanum tris(N,N'-diisopropylformamidinate), trimethylaluminum (TMA) and water. Capacitance-voltage measurements made on ALD MoN/LaAlO3/Si stacks showed humps especially at low frequencies. They were effectively removed by O2 treatment at 300 o C without affecting the dielectric constant (κ~15). The O2 treatment can be carried out either after deposition of a LaAlO3 film, or after each ALD cycle. The O2 treatment also lowered the leakage current from 80 mA cm-2 to 1 mA cm-2 for EOT = 1.3 nm. This indicates that oxygen vacancies are the main defects in as-deposited LaAlO3. Oxygen treated LaAlO3 is one of the best candidates for future high-κ dielectric material due to its low leakage, low defect density and abrupt interface with silicon.

Origin of Abnormal Dielectric Behavior and Chemical States in Amorphous CaCu3Ti4O12 Thin Films on a Flexible Polymer Substrate

“…Oxygen vacancies were reported to exist in crystalline CCTO films prepared by rf sputtering under low oxygen pressures . The decrease in the number of oxygen vacancies might contribute largely to minimizing the charge imbalance toward the stoichiometric CCTO structure in the amorphous structure and, thus, to influencing chemical states of cations. , …”

ALD Grown Rare-Earth High-k Oxides on Ge: Lowering of the Interface Trap Density and EOT Scalability

“…It is also possible to stabilize the higher tetragonal phase of ZrO 2 by using Ge atoms as dopant source (15). Addressing Atomic layer deposition (ALD) of La 2 O 3 promising results have been shown for the growth of La 2 O 3 , LaAlO 3 and HfO 2 /La 2 O 3 stacks, by using tris(N,N'-diisopropylformamidinate)-lanthanum in combination with water, ozone, and oxygen respectively (16,17,18).…”

Optimizing Band-Edge High-κ/Metal Gate n-MOSFETs with ALD Lanthanum Oxide Cap Layers: Oxidant and Positioning Effects

“…The lanthanum precursor used to fabricate the new devices discussed in this report was lanthanum tris(diisopropylformamidinate) (La(fmd) 3 ). ALD growth with this precursor using water and oxygen as the oxidants has been reported previously (7,11).…”