Bonded semiconductor memory device

Abstract

Disclosed are semiconductor devices and their fabrication methods. The semiconductor device comprises a lower substrate, a lower dielectric structure on the lower substrate, a memory cell structure between the lower substrate and the lower dielectric structure, a lower bonding pad in the lower dielectric structure, an upper dielectric structure on the lower dielectric structure, an upper substrate on the upper dielectric structure, a transistor between the upper substrate and the upper dielectric structure, and an upper bonding pad in the upper dielectric structure. A top surface of the lower bonding pad is in contact with a bottom surface of the upper bonding pad. The lower bonding pad and the upper bonding pad overlap the memory cell structure.