Characteristics of lithium phosphorous oxynitride thin films deposited by metal-organic chemical vapor deposition technique

Abstract

Lithium phosphorous oxynitride (LiPON) thin films are deposited by metal-organic chemical vapor deposition (MOCVD) technique using lithium dipivaloylmethane (Li(DPM)), triethyl phosphate (TEP) and NH3 as precursor materials, and effects of substrate temperature on the deposition rate and thin film properties are investigated. The deposition rate of LiPON films increases with rising substrate temperature, and as-deposited LiPON films exhibit the typical amorphous phase. The minimum activation temperature for the film deposition is 500 °C, and the activation energy is estimated to be 102.4 kJ mole−1. Concentrations of P and N element in the film are quite low at the temperature of 500 °C, but increase dramatically above 550 °C. Oxygen concentration in the film is inversely proportional to that of nitrogen, and the ratio of Li to P stays nearly constant with rising substrate temperature. The ratio of triply coordinated nitrogen to doubly coordinated nitrogen (Nt/Nd) gradually increases with rising substrate temperature, implying that the ionic conductivity is improved. The ionic conductivity reaches close to 2.95 × 10−7 Scm−1 as the substrate temperature is raised to 575 °C, and the value stays within the well-known value range (10−6–10−8 Scm−1) of LiPON films.