Comprehensive comparison of structural, electrical, and reliability characteristics of HfO2 gate dielectric with H2O or O3 oxidant

Abstract

The growth, composition, electrical characteristics, and reliability performance of high-k HfO2 dielectric films that were deposited by an atomic layer deposition technique are studied. The films were grown using tetrakis(ethylmethylamino)hafnium precursor and either H2O or ozone (O3) as the oxidant. When H2O was the oxidant, the resulting HfO2 film had a thinner interfacial layer than that obtained using the O3 oxidant, but the bulk HfO2 layer was of a poorer quality. Of the annealed HfO2 films with a comparable equivalent oxide thickness, the O3 oxidant-based HfO2 films had better electrical properties and reliability. The oxide charge density, the hysteresis, the leakage current, the breakdown electrical field, and the time to dielectric breakdown of the HfO2 film that was deposited with O3 oxidant were all better those of the film that was deposited with H2O oxidant. Additionally, the dynamic stress, including unipolar and bipolar stresses, increases the times to dielectric breakdown for both HfO2 films. However, the increase under bipolar stress was greater for the HfO2 films that were grown using the H2O oxidant because more detrapping occurred.