Very high frequency (∼100 MHz) plasma enhanced atomic layer deposition high-κ hafnium zirconium oxide capacitors near morphotropic phase boundary with low current density & high-κ for DRAM technology†

Abstract

Hafnium dioxide-based ferroelectric (FE) films are emerging as pivotal materials for advanced memory storage and neuromorphic computing, particularly in ultra-scaled dynamic random-access memory (DRAM) technologies. To meet the stringent DRAM performance requirements—dielectric constants (κ) exceeding 60 and leakage current densities below 10⁻⁶ A cm⁻² at 0.8 V—hafnium zirconium oxide (HZO) films engineered near the morphotropic phase boundary (MPB) are leading candidates. These films offer a favorable balance of high dielectric properties and reduced equivalent oxide thickness while managing leakage. However, film thinning often escalates leakage currents, presenting a significant design challenge. Moreover, interfacial damage induced by conventional deposition techniques can undermine dielectric stability. Here, we present a novel approach utilizing very high frequency (VHF, 100 MHz) plasma-enhanced atomic layer deposition (PE-ALD) to fabricate 4.5 nm HZO films with superior crystalline quality and minimized oxygen vacancies. This method yields an impressive dielectric constant of 64.47, markedly surpassing radio frequency-deposited counterparts. Notably, at elevated temperatures up to 389 K, the dielectric constant reaches 69.9, approaching the theoretical tetragonal-phase limit. Our results demonstrate the transformative potential of VHF PE-ALD in optimizing HZO film properties, establishing a compelling pathway for future high-performance DRAM applications.