FERROELECTRIC-SEMICONDUCTOR HETEROSTRUCTURES OBTAINED BY DIRECT WAFERBONDING

A novel fabrication process of ferroelectric-semiconductor heterostruc tures based on direct wafer bonding has been demonstrated. Polycrystal line Bi4Ti3O12 ferroelectric thin films were deposited on 3 in. silico n wafers using chemical solution deposition. The films were polished a nd then directly bonded to silicon wafers in a micro-cleanroom. After thermal annealing in air at 500 degrees C for 12 h, the bonding energy increases up to 1.5 J/m(2). High resolution transmission electron mic roscopy shows the difference between the bonded and reacted interfaces . Obtaining a metal-ferroelectric-silicon (MFS) structure containing t he ferroelectric-Si bonded interface was achieved by polishing down an d etching the handling wafer. The Bi4Ti3O(12) film kept its ferroelect ric properties as shown by C-V measurement. (C) 1997 American Institut e of Physics.