METHOD FOR FABRICATING DEEP TRENCH IN SEMICONDUCTOR SUBSTRATE

摘要

PURPOSE: A method for fabricating a deep trench in a semiconductor substrate is provided to remarkably increase the lower width of the deep trench without forming a polymer in a plasma chamber, by increasing the flow rate of plasma gas while chlorine gas is added to etching plasma gas composition at a predetermined flow rate after the outline of a neck is formed. CONSTITUTION: A pad stack-type layer(15) is formed on the substrate(10). A penetration hole is formed in the pad stack-type layer by using a photolithography process. The second plasma etching process in which the second etching composition is used at the second predetermined set of flow rate is performed to form an upper trench section in the substrate. The third plasma etching process in which the third etching composition including Cl2 is used at the third predetermined set of flow rate is performed to form a trench section having an enlarged width in the substrate under the trench section.