Work

Low-Temperature RF Magnetron Sputtering of TiW Thin Films: Effects of the Bulk Plasma Characteristics on Film Growth

Year: 2025

Type: article

Abstract: TiW thin films with superior surface properties were deposited at room temperature using RF magnetron sputtering under low-temperature process conditions. The correlation between bulk plasma characteristics and thin-film properties was investigated as a function of applied RF power (200–600 W) and process pressure (1–10 mTorr). Plasma potential and ion density were measured using a Langmuir probe, while deposition rate, surface roughness, sheet resistance, and crystallinity were evaluated. Increasing the applied RF power simultaneously increased plasma potential and ion density, enhancing ion bombardment energy at both the target and substrate, which improved sputtering efficiency and deposition rate. Under low-temperature deposition, thermal stress induced by differences in thermal expansion between the film and substrate was minimal. However, limited surface diffusion of adatoms caused incomplete coalescence of nucleation islands, adversely affecting film crystallinity. Refractory metals such as tungsten exhibit strong dependence of residual stress and microstructure on deposition conditions, highlighting the importance of plasma and process parameters on TiW film properties. When RF power was increased, the enhancement in deposition rate outweighed the effect of increased ion energy, leading to tensile stress from void formation dominating over compressive stress induced by high-energy ions. This also contributed to increased grain size and reduced sheet resistance. In contrast, variations in process pressure had minor effects on plasma characteristics, resulting in limited changes in the deposited film properties.

Source: Applied Sciences

DOI: 10.3390/app152212300

Authors: Chiyun Bang, Chang Yeong Ji, Ju-Hong Cha

Institution: Gyeongsang National University

Language: English

Topic: Metal and Thin Film Mechanics

Subfield: Mechanics of Materials

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,896

Funders: Gyeongsang National University, Ministry of Trade, Industry and Energy