High-quality BeO films fabricated using discrete feeding plasma-enhanced atomic layer deposition

Abstract

In this study, we fabricated high-quality beryllium oxide (BeO) films using discrete-feeding plasma-enhanced atomic layer deposition (DF-PEALD). BeO has exceptionally high thermal conductivity (330 W/m-K), a large bandgap energy, and a high dielectric constant, making it an optimal dielectric that can solve the thermal problems caused by the miniaturization of transistors. In atomic layer deposition (ALD), the physically adsorbed precursors and byproducts present during precursor injection act as a barrier to the full saturation of the substrate surface. The discrete feeding method (DFM) is a process that divides the precursor feeding and purge steps into several individual units without changing the overall process. This mitigates the effects of in-process screening and suppresses the formation of interfacial layers and carbon impurities. The grain size of the BeO fabricated using DF-PEALD was found to be 31.3 % higher than that of BeO fabricated using plasma-enhanced atomic layer deposition (PEALD) without the DFM, and its density (3.01 g/cm3) more closely matched that of the bulk. The dielectric constant of the BeO films fabricated using DF-PEALD was 8.8, the bandgap energy was 8.1 eV, and the leakage current density was 1.21 x 10-9 A/cm2 at -1 MV/cm.