Patent ID: 7344995

Claim:
A method for preparing a structure with high aspect ratio, comprising steps of: depositing a first layer made of dielectric material or metal by a chemical vapor deposition process on a conductive layer of a substrate; forming at least one photoresist pattern on the first layer; etching the first layer to form a first mask on the substrate; performing a first etching process to remove a portion of the substrate uncovered by the first mask to form at least one concavity; forming a second mask on the first mask by a process comprising at least a step of depositing a second layer on the substrate and a step of removing a portion of the second layer on the surface of the at least one concavity, wherein the step of removing a portion of the second layer on the surface of the at least one concavity is a dry etching process using etching gases including octafluorocyclopentene, argon, carbon tetrafluoride and oxygen; and performing a second etching process to extend the depth of the at least one concavity into the substrate.