Methods and apparatuses for void-free tungsten fill in three-dimensional semiconductor features

A method of filling a 3-D structure of a partially manufactured semiconductor substrate, the 3-D structure comprising sidewalls, a plurality of openings in the sidewalls leading to a plurality of features having a plurality of interior regions fluidically accessible through the openings, the method comprising:

• providing a substrate having the 3-D structure, the 3-D structure already having a first layer of a tungsten-containing material at least partially covering its sidewalls and/or openings in its sidewalls, and partially filling the plurality of interior regions, but with a portion of the plurality of interior regions left unfilled by the first layer;
• etching vertically to remove portions of the first layer of the tungsten-containing material from the sidewalls and/or openings in the sidewalls without substantially removing portions of the first layer from the plurality of interior regions;
• etching horizontally to remove portions of the first layer of the tungsten-containing material from the plurality of interior regions;
• and
• depositing a second layer of the tungsten-containing material after etching horizontally and vertically.

An apparatus for filling a 3-D structure of a partially manufactured semiconductor substrate with a tungsten-containing material, the 3-D structure comprising sidewalls, a plurality of openings in the sidewalls leading to a plurality of features, the plurality of features having a plurality of interiors fluidically accessible through the plurality of openings, the apparatus comprising:

• a processing chamber;
• a substrate holder within the processing chamber configured to hold the substrate having the 3-D structure;
• one or more gas inlets configured to introduce a tungsten-containing precursor and a reducing agent into the processing chamber;
• a power supply configured to generate and maintain an ionized plasma within the processing chamber;
• and
• a controller having instructions in the form of machine readable code for operating the one or more gas inlets and power supply, the controller configured to execute the instructions, the instructions comprising:
• instructions for depositing a first layer of the tungsten-containing material within the 3-D structure such that the first layer partially fills the plurality of interior regions of the 3-D structure;
• instructions for etching vertically and horizontally after depositing the first layer of the tungsten-containing material, the vertical etching comprising removing portions of the first layer from the sidewalls using a first activated etching material without substantially removing portions of the first layer from the plurality of interior regions, the horizontal etching comprising removing portions of the first layer from the plurality of interior regions using a second activated etching material;
• and
• instructions for depositing a second layer of the tungsten-containing material within the 3-D structure after etching vertically and horizontally such that the second layer fills at least a portion of the interior regions left unfilled by the first layer.