Even tungsten etch for high aspect ratio trenches

摘要

Methods of evenly etching tungsten liners from high aspect ratio trenches are described. The methods include ion bombardment of a patterned substrate having high aspect ratio trenches. The ion bombardment includes fluorine-containing ions and the ion bombardment may be stopped before breaking through the horizontal liner portion outside the trenches but near the opening of the trenches. The methods then include a remote plasma etch using plasma effluents formed from a fluorine-containing precursor. Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents react with the tungsten. The plasmas effluents react with exposed surfaces and remove tungsten from outside the trenches and on the sidewalls of the trenches. The plasma effluents pass through an ion suppression element positioned between the remote plasma and the substrate processing region.

主权项

1. A method of etching tungsten, the method comprising:
transferring a patterned substrate into a substrate processing region, wherein the patterned substrate has a tungsten lining layer coating a high aspect ratio trench having a depth more than five times a width of the high aspect ratio trench, wherein the high aspect ratio trench is disposed between two adjacent stacks and one or both of the two adjacent stacks comprises at least ten alternating layers of dielectric and tungsten; flowing a first fluorine-containing precursor into the substrate processing region while applying a bias plasma power to bombard the patterned substrate with fluorine-containing ions; flowing a second fluorine-containing precursor into a remote plasma region fluidly coupled to a substrate processing region via perforations in a perforated plate; forming a remote plasma in the remote plasma region to produce plasma effluents from the second fluorine-containing precursor and flowing the plasma effluents into the substrate processing region through the perforations; and etching the tungsten lining layer, wherein, after etching the tungsten lining layer, a top sidewall thickness of the tungsten lining layer measured on a sidewall of the high aspect ratio trench near the opening of the high aspect ratio trench is within 20% of a bottom sidewall thickness of the tungsten lining layer measured on the sidewall of the high aspect ratio trench near the bottom of the high aspect ratio trench.