Masking process and structures formed thereby

摘要

A method, e.g., of forming and using a mask, includes forming an inverse mask over a dielectric layer; forming a mask layer conformally over the inverse mask; removing horizontal portions of the mask layer; and after removing the horizontal portions, simultaneously etching the inverse mask and vertical portions of the mask layer. The etching the inverse mask is at a greater rate than the etching the vertical portions of the mask layer. The etching the inverse mask removes the inverse mask, and the etching the vertical portions of the mask layer forms a mask comprising rounded surfaces distal from the dielectric layer. Recesses are formed in the dielectric layer using the mask. Locations of the inverse mask correspond to fewer than all locations of the recesses.

主权项

1. A method comprising:
forming an inverse mask over a dielectric layer, wherein the inverse mask comprises titanium nitride; forming a mask layer conformally over the inverse mask, wherein the mask layer comprises titanium oxide, oxidized titanium nitride, or a combination thereof; removing horizontal portions of the mask layer; after removing the horizontal portions, simultaneously etching the inverse mask and vertical portions of the mask layer using Cl2 gas as an etchant, a ratio of a rate of the etching the vertical portions of the mask layer to a rate of the etching the inverse mask being in a range from 3:5 to 3:7, the etching the inverse mask removing the inverse mask, the etching the vertical portions of the mask layer forming a mask comprising rounded surfaces distal from the dielectric layer by removing respective portions of the vertical portions of the mask layer; and forming recesses in the dielectric layer using the mask, locations of the inverse mask corresponding to fewer than all locations of the recesses.