High-throughput methodology for the realization of high-entropy sub-nm equivalent-oxide-thickness high-dielectric-constant Ba(Ti,Zr,Ta,Hf,Mo)O3 film-based metal-oxide-semiconductor-related devices

Abstract

This paper reports the use of a high-throughput sputtering technique for the fabrication of high-entropy high-dielectric-constant (high-k) Ba(Ti,Zr,Ta,Hf,Mo)O3 film libraries on Si substrates and sub-nm equivalent-oxide-thickness (EOT) metal−oxide−semiconductor (MOS) devices and metal−oxide−semiconductor field-effect transistors (MOSFETs). The elemental variations and amorphous microstructures are characterized using high-throughput X-ray fluorescence (XRF) and X-ray diffraction, respectively. The film library was patterned into 100 MOS configurations and the films with (Ba + Ti) = 0.41−0.47 at.%, (Mo + Zr) = 0.28−0.34 at.%, and (Ta + Hf) = 0.23−0.3 at.% exhibited favorably high k (325−374) and low tan δ (0.01−0.08) values with an impressive EOT ≈ 0.8−0.94 nm. The resulting MOSFETs after the rapid thermal annealing (RTA) exhibited excellent characteristics: an on/off current ratio of 8 × 106, saturated field-effect mobility of 138.4 cm2 V−1 s−1, a threshold voltage (VT) of 0.03 V, a subthreshold swing of 0.062 V⋅dec−1, and low interfacial defects of approximately 5.6 × 1010 eV cm−2. Small ΔVT and negligible changes in the maximum drain current were observed for the MOSFETs under various positive and negative gate-bias stress conditions before and after the RTA. Our devices outperformed various reported transistors, indicating the potential of the Ba(Ti,Zr,Ta,Hf,Mo)O3 films for use in a gate-first process for advanced gate stack-related devices.