Dielectric properties and reliability enhancement of atomic layer deposited thin films by in situ atomic layer substrate biasing

Abstract

A novel “atomic layer substrate biasing (ALSB)” technique is proposed to improve the dielectric properties including film density, dielectric constant (K), and leakage current density (J_g) and the reliability of nanoscale thin films. In the ALSB process, in situ Ar plasma generated by substrate biasing is layer-by-layer introduced into each cycle of atomic layer deposition. Energy delivery from the plasma toward the as-deposited layer boosts the migration of adatoms, leading to ∼10% increase of the film density, ∼3-order-of-magnitude reduction of J_g, and an increment of K being as large as 40.7 of a ZrO₂ layer of ∼5 nm. The reliability enhancement upon the ALSB treatment is demonstrated by constant-voltage-stress (CVS) and the time-dependent-dielectric-breakdown (TDDB) tests, which confirm the suppression of stress-induced traps and a high electric field of 4.7 MV cm⁻¹ projected for a 10 year lifetime. Significant improvements in the film density, J_g, K, and the reliability indicate that ALSB is a highly effective technique to modify the quality of ALD-deposited thin films, which can be widely used in a variety of fields including energy saving, green energy, nanoelectronics, and biomedical applications.