Characterization of Trap States at Silicon-On-Insulator (SOI)/Buried Oxide (BOX) Interface by Back Gate Transconductance Characteristics in SOI MOSFETs

Abstract

We characterized trap states at silicon-on-insulator (SOI)/buried oxide (BOX) interfaces in epitaxial layer transfer (ELTRAN) wafers and in low-dose separation by implanted oxygen (SIMOX) wafers. We formulated a simple analytical form to obtain the distribution of density of trap states from a comparison of the experimental transconductance and simulated transconductance of SOI metal oxide semiconductor field effect transistors (MOSFETs). We observed dips in back gate transconductance in MOSFETs on low-dose SIMOX wafers. Consequently, we concluded that “acceptor-like electron traps” with the density of 5 ×1012 cm-2·eV-1 near the conduction band edge Ec and “donor-like hole traps” with the density of 1012 cm-2·eV-1 near the valence band edge Ev are distributed in the forbidden band of Si at SOI/BOX interfaces in low-dose SIMOX wafers, while the trap density at SOI/BOX interfaces is less than 1011 cm-2·eV-1 in ELTRAN wafers. We also found that the kink effect is suppressed in MOSFETs on low-dose SIMOX wafers with a high density of trap states at the SOI/BOX interface.