Direct wafer bonding and layer transfer-a new approach to integration of ferroelectric oxides into silicon technology

Abstract

Metal-ferroelectric-silicon (MFS) structures were fabricated by a layer transfer process and direct wafer bonding (DWB) and by direct deposition of ferroelectric films onto Si. Detailed transmission electron microscope (TEM) investigations revealed that a direct wafer bonding and layer transfer process yields good quality ferroelectric/Si interfaces. C-V characteristics and interface trap measurements show a large difference for Au-ferroelectric-Si structures fabricated by bonding or by direct deposition. For directly deposited interfaces the trap densities are ranging from 2×10¹²cm⁻²eV⁻¹ for SBT/Si to 2×10¹³ cm⁻²eV⁻¹ for PZT/Si. For bonded interfaces, irrespective of the top ferroelectric layer, the trap density is about 4×10¹¹cm⁻²eV⁻¹.

Keywords:

• metal-ferroelectric-silicon structures
• interface trap density
• direct wafer bonding
• TEM analysis