DRAM stack capacitor with ladder storage node

摘要

A method, and resultant structure, is described for fabricating a DRAM (Dynamic Random Access Memory) cell having a stack capacitor with a ladder storage node, connected to a MOS (Metal Oxide Semiconductor) transistor with source and drain regions, to form a DRAM cell. A bottom electrode is connected to and extends up from the source region of the transistor, and has a top surface with a central cavity, and side surfaces extending down from the top surface in a step-like manner. These step-like sides are formed by a repeated two-step process of removing a portion of the vertical walls of a photoresist mask and removing a portion of the top surface of a layer of polysilicon from which the bottom electrode is formed. There is a capacitor dielectric over the bottom electrode. A top electrode is formed over the capacitor dielectric.