Direct wafer bonding and layer transfer for ferroelectric thin film integration

Abstract

A novel fabrication process of ferroelectric-semiconductor heterostructures based on direct wafer bonding (DWB) and layer transfer is proposed. Metal-ferroelectric-silicon (MFS) structures were fabricated by both layer transfer process and 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. Interface trap measurements show a large difference for MFS structures fabricated by bonding or by direct deposition, respectively. The trap density values were ranging from 2×10¹² cm⁻²eV⁻¹ for SBT/Si directly deposited to 4×10¹¹ cm⁻²eV⁻¹ for SBT/Si bonded interfaces.

Keywords:

• layer transfer
• direct wafer bonding
• metal-ferroelectric-silicon structures
• interface trap density