Anisotropic gap etch

摘要

A method of anisotropically dry-etching exposed substrate material on a patterned substrate is described. The patterned substrate has a gap formed in a single material made from, for example, a silicon-containing material or a metal-containing material. The method includes directionally ion-implanting the patterned structure to implant the bottom of the gap without implanting substantially the walls of the gap. Subsequently, a remote plasma is formed using a fluorine-containing precursor to etch the patterned substrate such that either (1) the walls are selectively etched relative to the floor of the gap, or (2) the floor is selectively etched relative to the walls of the gap. Without ion implantation, the etch operation would be isotropic owing to the remote nature of the plasma excitation during the etch process.

主权项

1. A method of etching a patterned substrate, the method comprising:
ion implanting the patterned substrate, wherein ion implanting the patterned substrate comprises ion implanting an exposed undoped bottom portion of a gap in the patterned substrate with carbon, wherein both the exposed undoped bottom portion and an exposed undoped sidewall portion of the gap comprise silicon, wherein the exposed undoped sidewall portion and the exposed undoped bottom portion are formed from a single material having the same stoichiometry prior to ion implantation, and wherein the ion implantation dopes the exposed undoped bottom portion to form an exposed doped bottom portion but the ion implantation does not dope the exposed undoped sidewall portion; placing the patterned substrate in a substrate processing region of a substrate processing chamber; combining a fluorine-containing precursor with a hydrogen-containing precursor in a remote plasma region fluidly coupled to the substrate processing region by way of a showerhead while forming a remote plasma in the remote plasma region to produce plasma effluents; and anisotropically etching the patterned substrate such that the exposed undoped sidewall portion etches at a greater etch rate than the exposed doped bottom portion.