Abstract: The present invention discloses a method for preparing a structure with high aspect ratio, which can be a trench or a conductor. A first mask is formed on a substrate, and a first etching process is performed to remove the substrate uncovered by the first mask to form at least one concavity. A second mask is formed on the surface of the prepared structure, a second etching process is then performed to remove the second mask on the concavity, and a third etching process is performed subsequently to extend the depth of the concavity into the substrate. To prepare a conductor with high aspect ratio in the substrate, the first mask and the second mask are preferably made of dielectric material or metal. In addition, to prepare a trench with high aspect ratio in a silicon substrate, the first mask and the second mask are preferably made of dielectric material.

Abstract: A method of patterning a metal line and removing the polymer layer that forms on the metal lines sidewalls in an important post etch-polymer removal step (e.g., step 4). A semiconductor structure and an overlying dielectric layer, a first barrier layer, a metal layer; a second barrier layer and resist pattern are provided. A four step etch process is performed in sequence in the same etch chamber. In a first etch step (A), we etch through the second barrier layer using a B and Cl containing gas and a Cl containing gas in a reactive ion etch to form a first polymer layer over the sidewall of the second barrier layer. In a second etch step (B), the metal layer is etched exposing the first barrier layer to form a second polymer over the first polymer and the sidewall of the metal layer; the second etch step performed using a B and Cl containing gas and a Cl containing gas. In a third etch step (C), the first barrier layer is etched to form a third polymer layer over the first and second polymer layers.