Metal recess for semiconductor structures

An etching method comprising:

• flowing an oxygen-containing precursor into a first semiconductor processing chamber, wherein a substrate is positioned within the first semiconductor processing chamber, wherein the substrate comprises a trench formed between two vertical columns and tungsten slabs arranged within a plurality of recesses defined by at least one of the two vertical columns, wherein at least two of the tungsten slabs are connected by tungsten lining a portion of sidewalls of the trench, and wherein the substrate further comprises metal nitride liners disposed adjacent to the tungsten slabs and the tungsten connecting the at least two of the tungsten slabs;
• oxidizing, in the first semiconductor processing chamber, the tungsten connecting the at least two of the tungsten slabs with the oxygen-containing precursor;
• oxidizing, in the first semiconductor processing chamber, at least portions of the metal nitride liners with the oxygen-containing precursor;
• flowing a halide precursor into a second semiconductor processing chamber, wherein the halide precursor comprises at least one of tungsten chloride or tungsten fluoride;
• laterally etching, in the second semiconductor processing chamber, the tungsten oxidized in the first semiconductor processing chamber from the sidewalls of the trench;
• and
• laterally etching, in the second semiconductor processing chamber, the portions of the metal nitride liners oxidized in the first semiconductor processing chamber.

An etching method comprising:

• flowing an oxygen-containing precursor into a semiconductor processing chamber, wherein a substrate is positioned within the semiconductor processing chamber, wherein the semiconductor processing chamber includes a heating source, wherein the substrate comprises a trench formed between two vertical columns and tungsten slabs arranged within a plurality of recesses defined by at least one of the two vertical columns, wherein at least two of the tungsten slabs are connected by tungsten lining a portion of sidewalls of the trench, and wherein flowing the oxygen-containing precursor comprises pulsing the flow of the oxygen-containing precursor;
• oxidizing the tungsten connecting the at least two of the tungsten slabs with the oxygen-containing precursor while the substrate is positioned at a first distance from the heating source;
• pausing the flow of the oxygen-containing precursor;
• flowing a halide precursor into the semiconductor processing chamber;
• resuming the flow of the oxygen-containing precursor subsequent to the flow of the halide precursor;
• and
• laterally etching the oxidized tungsten from the sidewalls of the trench while the substrate is positioned at a second distance from the heating source, wherein the second distance is greater than the first distance.