Method of making greek letter psi shaped capacitor for DRAM circuits

摘要

A method of forming a capacitor having a cross section shape similar to the Greek letter psi. The shape of the capacitor plate provides a high capacitance using a modest amount of chip area. A capacitor hole is etched in a thick layer of a first dielectric. A layer of polysilicon is formed on the dielectric layer covering the sidewalls and bottom of the capacitor hole. A second dielectric is then used to fill the hole. A contact hole in the second dielectric extends to the contact region of the wafer and is filled with a polysilicon plug. The polysilicon plug and the polysilicon covering the sidewalls and bottom of the capacitor hole form the first capacitor plate. A layer of hemispherical grain polysilicon can be used to further increase the surface area of the first capacitor plate.