Patent ID: 6306772
Filing Date: 2001-10-23
Classification: H01L

Abstract:
A method for forming a deep trench in a semiconductor substrate, comprising the steps of:(a) forming a pad stacked layer on a substrate;(b) forming a through hole in said pad stacked layer using a photolithography process;(c) performing a second plasma etching process to form an upper trench section in said substrate, said second plasma etching process being performed using a second etching composition which comprises HBr, NF.sub.3, and a mixture of He and O.sub.2 at a second predetermined set of flow rates; and(d) performing a third plasma etching process to form a width-enlarged trench section in said substrate below said upper trench section, said third plasma etching process being performed using a third etching composition which comprises HBr, NF.sub.3, Cl.sub.2, and a mixture of He and O.sub.2 at a third predetermined set of flow rates.