Method of forming enhanced capacitance trench capacitor

Abstract

A method of fabricating a trench capacitor is provided in which a material composition of a semiconductor region of a substrate varies in a quantity of at least one component therein such that the quantity alternates with depth a plurality of times between at least two different values. For example, a concentration of a dopant or a weight percentage of a second semiconductor material in a semiconductor alloy can alternate between with depth a plurality of times between higher and lower values. In such method, the semiconductor region can be etched in a manner dependent upon the material composition to form a trench having an interior surface which undulates in a direction of depth from the major surface of the semiconductor region. Such method can further include forming a trench capacitor having an undulating capacitor dielectric layer, wherein the undulations of the capacitor dielectric layer are at least partly determined by the undulating interior surface of the trench. Such trench capacitor can provide enhanced capacitance, and can be incorporated in a memory cell such as a dynamic random access memory ('DRAM') cell, for example.