Method of forming deep trench capacitors

摘要

A vertical trench in a silicon wafer for use in forming the storage capacitor of a DRAM is etched by reactive ion etching in a manner to have a profile that has multiple waists. This profile is obtained by varying the rate of flow of coolant in the base member on which the silicon wafer is supported during the reactive ion etching to vary the temperature of the silicon wafer during the etching. Alternatively, the multiple waists are achieved by either by varying the ratio of the different gases in the etching chamber or the total gas pressure in the chamber.