Highly Stacked GeSn Nanosheets by CVD Epitaxy and Highly Selective Isotropic Dry Etching
Journal
IEEE Transactions on Electron Devices
Journal Volume
69
Journal Issue
4
Pages
2130-2136
Date Issued
2022
Author(s)
Abstract
The eight stacked Ge0.9Sn0.1 ultrathin bodies down to 3 nm with high {I}-{text {ON}}/I-{text {OFF}} and eight stacked Ge0.9Sn0.1 thick nanosheets with high {I}-{text {ON}} per stack are demonstrated. For the eight stacked Ge0.9Sn0.1 ultrathin bodies, the 50 epilayers, including Ge0.9Sn0.1 channels, double Ge0.97Sn0.03/Ge (8 nm/3 nm) caps, heavily B-doped (2E21 cm-3) Ge sacrificial layers (SLs), and undoped Ge buffer were epitaxially grown to reach high inter-channel uniformity with the co-optimization of epitaxy and radical-based highly selective isotropic dry etching (HiSIDE). The thin double Ge0.97Sn0.03 caps can provide sufficient etching selectivity and stabilize the channel to prevent the channels from bending and buckling. The neutral radicals can isotropically etch the Ge0.97Sn0.03/Ge caps, Ge:B SLs, and Ge buffer to form the highly uniform eight stacked Ge0.9Sn0.1 ultrathin bodies. The record {I}-{text {ON}}/{I}-{text {OFF}} of 1.4 times 10{{7}} at {V}-{text {DS}} ,,=,,-0.05 V is achieved among GeSn 3-D pFETs due to the quantum confinement. For the eight stacked Ge0.9Sn0.1 thick nanosheets, the record {I}-{text {ON}} of 92 mu text{A} per stack at {V}-{text {OV}} = {V}-{text {DS}} = -0.5 V is achieved among GeSn 3-D pFETs. Thick nanosheets can provide higher mobility than ultrathin bodies due to the reduced surface roughness scattering. © 1963-2012 IEEE.
Subjects
Chemical vapor deposition; GeSn; nanosheets; quantum confinement; radical-based highly selective isotropic dry etching (HiSIDE); ultrathin body
Other Subjects
Chemical vapor deposition; Computer circuits; Epitaxial growth; Etching; Germanium; Logic gates; Quantum confinement; Semiconductor alloys; Surface roughness; Chemical vapour deposition; Epitaxially grown; Germaniums (Ge); Isotropics; Noise measurements; Radical-based highly selective isotropic dry etching; Rough surfaces; Sacrificial layer; Ultrathin body; Ultrathin body.; Nanosheets
Type
journal article