Novel fabrication process of silicon nano-field effect transistor for ultrasensitive detection analysis

N.N. Mishra, E.C. Cameron
University of Idaho, US

Keywords: nanotechnology, nano transistor, detection, hafnium oxide, silicon nanowire, dielectric

Summary:

Silicon nano-field effect transistor (nano-FET) where fabricated using minimum cost effective steps. The nano-FET devices were well improved on this project. Several p and n type of polysilicon and monocrystalline silicon wafers were used in the process development of these devices. The medium Boron dopant levels on the devices layer (mono silicon) were shown the highest sensitivity in both types of the wafers. We assume that there was at least 5-10% loss of boron dopent during specific Cl plasma etch. The current-voltage (C-V) test of the polysilicon nanowire (20-150 nm size) based devices shown as variable field effect resistor whereas mono-crystal silicon devices have shown excellent NMOS type nano-FET. The schottky effect was also eliminated by selecting Cr/Au or Cr/Pt as contact metal to the p-type nanowire. Various insulator layers were also deposited on the nanowire surface but only thin hafnium oxide (~10nm) and thermal SiO2 (~20nm) were shown outstanding insulating characteristics with negligible current leakage whereas device with alumina and silicon nitride, were failed. Based on the current device we assume to have simple NMOS type Si nano-FET characteristics with minimal process steps. These devices can be used in various chemical and biological detection analyses.