Characteristics of LiNbO3 memory capacitors fabricated using a low thermal budget process

Abstract

We investigated LiNbO3 metal ferroelectric semiconductor (MFS) capacitors because of the following advantages: a low interface trap density, a low interaction with Si substrate, and a large remanent polarization. Ferroelectric LiNbO3 thin films were grown directly on p-type Si(100) substrates for metal ferroelectric semiconductor field effect transistor (MFSFET) applications. Low temperature film growth and post rapid thermal anneal (RTA) treatments improved the leakage current of films while keeping other properties almost the same as high substrate temperature grown samples. We reduced the leakage current density of LiNbO3 films from 10−5 A/cm2 to 10−7 A/cm2 with RTA treatment. LiNbO3 MFS capacitors exhibited a breakdown electric field of greater than 500 kV/cm. RTA treatment above 600°C converted LiNbO3 films from amorphous to polycrystalline states with (012), (015), (022), and (023) planes. The polycrystalline LiNbO3 MFS capacitors illustrated the ferroelectric switching characteristics with a memory window ranging from 0.6 to 1.9 V. We obtained a remanent polarization of 2.74 μC/cm2 and a coercive field of 170 kV/cm using the LiNbO3 MFS capacitors.