Capacitive effective thickness of a few nanometers by atomic layer deposition and device performance in Ge gate-all-around fin field effect transistors

Chu Lin Chu, Bo Yuan Chen, Yiin Kuen Fuh

Research output: Contribution to journalArticlepeer-review

Abstract

Ge gate-all-around fin field-effect transistors (Ge FinFETs) with a capacitive effective thickness of a few nanometers have been successfully achieved via atomic-layer-deposited (ALD) high-dielectric Al2O3 on GeO2/Ge and by adopting low-cost thermo ALD equipment. The MOS interface properties of the ZrO2 or Al2O3/GeO2/Ge structures have been studied systematically. It has been found that a GeO2 interfacial layer that is greater than approximately 2.5 nm results in a significant degradation of the MOS interfaces, while an equivalent oxide thickness of <3 nm is still possible while maintaining good GeO2/Ge interface quality. The Ge FinFET's value has been demonstrated with the Al2O3/GeO2/Ge gate stack prepared using a thermal ALD layer of Al2O3. The experimental results indicate that the MOS interface quality obtained with the technique developed for high-permittivity/Ge gate stacks is also extremely useful for the fabrication of triangle-fin complementary metal oxide semiconductor devices. An Ion/Ioff ratio of 3.2×104 and a subthreshold swing of 103 mV/dec were obtained for the triangular n-type Ge gate-all-around FET with (111) sidewalls. The drain current at VGS-VT=VDS=-1.5 V is 88 mA/mm.

Original languageEnglish
Article number044501
JournalJournal of Micro/Nanolithography, MEMS, and MOEMS
Volume14
Issue number4
DOIs
StatePublished - 1 Oct 2015

Keywords

  • atomic layer deposited
  • capacitive effective thickness
  • field effect transistors
  • Ge gate-all-around

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