In situ and ex situ hardmask process for STI with oxide collar application

Abstract

A method or process for etching a trench in an IC structure is disclosed. The IC structure might be comprised of a plurality of different component materials arranged proximate to one another, all of which need to be etched down to a target level. A first etching chemistry is applied which preferentially etches a one type of component material. A second etching chemistry is applied which preferentially etches another type of component material. The method or process toggles back and forth between the etching chemistries until the target level is reached. The toggling techniques serves to maintain the profiles of the different component materials. One component material might also be embedded, as a collar or otherwise, around another component material. The toggling technique can serve to modulate the height, level, or shape of one material relative to another material. The toggling steps can be performed in situ or ex situ. The toggling technique can be used with different mask materials, including a photoresist or a hardmask over the IC structure.

Dependencies are inferred from the claim text.