UNTER DER OBERFLAECHE EINER SPEICHERPLATTE ANGEORDNETE SPEICHERZELLE

摘要

A submerged storage plate capacitor in a one-transistor dynamic random access memory is formed in a submerged portion of a trench in the body of a silicon substrate by a two step process. A shallow trench (11) is first etched in the substrate and an oxide layer (15) is deposited therein. The bottom portion of the oxide layer in the shallow trench is etched away defining a second deeper trench (19). The internal walls of the deeper trench are heavily doped by boron thereby to form a submerged capacitor storage region (13) in the substrate. A capacitor dielectric oxide layer (15) formed in the trench separates a n+ doped polysilicon core (14) serving as one plate of the submerged capacitor. A conductive piece of polysilicon interconnects the polysilicon core with the source region of a transfer transistor formed on the surface of the substrate. <IMAGE>