Method of making corrugated cell contact

摘要

A method of forming a cell contact that has improved structural strength and break-down resistance and a cell contact produced by such method are provided. The method utilizes an oxide spacer consisting of a plurality of oxide layers deposited by two alternating methods of thermal CVD and plasma CVD. After a straight contact opening is first etched by a plasma etching technique, the hole is again etched by an etchant such as hydrogen fluoride which has a high selectivity toward oxide layers formed by the plasma CVD method and a low selectivity toward oxide layers formed by the thermal CVD method. As a result, a contact opening having a corrugated side-wall is formed and into which a polysilicon is deposited to substantially fill the hole. A cell contact having a corrugated side-wall configuration is thus formed which presents improved structural rigidity and break-down resistance. A layer of rugged polysilicon layer may optionally be deposited before the deposition of the polysilicon into the contact opening to further increase the surface area of the cell contact.