Carbon based depositions used for critical dimension control during high aspect ratio feature etches and for forming protective layers

A method for fabricating a semiconductor substrate, the method comprising:

• (i) depositing an amorphous carbon material forming a liner onto sidewalls of a feature vertically etched into one or more layers on a semiconductor substrate;
• (ii) at least partially simultaneous etching, during the deposition of the amorphous carbon material, excess deposits of the amorphous carbon material depositing in a hole defining the feature and upper regions of the sidewalls of the feature;
• and
• (iii) after depositing the amorphous carbon material onto the sidewalls of the feature, performing additional vertical etching of the feature, wherein the amorphous carbon material resists lateral etching of the sidewalls of the feature during the additional vertical etching.

A method of fabricating a semiconductor substrate, the method comprising:

• (a) vertically etching a feature having an opening, sidewalls and a depth into one or more layers formed on the semiconductor substrate;
• (b) depositing a liner material onto the sidewalls of the feature;
• (c) performing an etch of a carbon mask used to define the opening of the feature, the etch:
• (i) removing excess deposits of the liner material that has collected in the opening of the feature defined by the carbon mask;
• and
• (ii) shaping the carbon mask in a vicinity of the opening of the feature;
• and
• (d) iterating (a), (b) and (c) until the feature has reached a desired depth into the one or more layers formed on the semiconductor substrate.

A method performed within a substrate processing chamber, the method comprising:

• fabricating a vertical feature formed on a substrate in the processing chamber, the vertical feature having an opening, sidewalls and a depth;
• depositing amorphous carbon material on the substrate in the processing chamber, the amorphous carbon material deposited on the sidewalls of the vertical feature and forming a plug within the opening of the vertical feature, wherein the amorphous carbon material partially fills the vertical feature in a section below the plug, and wherein the amorphous carbon material is deposited non-conformally so that the amorphous carbon material is thinner near the depth of the vertical feature and thicker near the opening of the vertical feature;
• and
• etching back a portion of the plug to create a recess above the plug.